Arbutus Biopharma Q1 2024 Earnings Call Transcript

Quartr
Provided by Quartr
May 2, 2024

There are 11 speakers on the call.

Operator

day and thank you for standing by. Welcome to the Arbutus Biopharma 20 24 First Quarter Financial Results and Corporate Update Conference Call. At this time, all participants are in a listen only mode. After the speakers' presentation, there will be a question and answer session. To ask a question during the session, you will need to press star 11 on your telephone.

Operator

You will then hear an automated message advising your hand is raised. 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.

Speaker 1

Thank you, Andrea. Good morning, everyone, and thank you for joining Arbutus' Q1 2024 Financial Results and Corporate Update Call. Joining me today from the Arbutus executive team are Mike McElholl, Interim President and Chief Executive Officer Doctor. Karen Sims, Chief Medical Officer David Hastings, Chief Financial Officer and Doctor. Mike Sofia, Chief Scientific Officer.

Speaker 1

Mike McElholl 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 Q1 2024 financial results. After our prepared remarks, we will open the call for Q and 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 ks, 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 McElholl.

Speaker 1

Mike?

Speaker 2

Thanks, Lisa. Good morning, everyone, and thank you for joining us today. This morning, we issued 2 press releases, one announcing the end of year retirement of our Co Founder and Chief Scientific Officer, Doctor. Mike Sofia and 1 with our Q1 of 2024 financials and a corporate update. I want to pass the call

Speaker 3

to Mike Sofia to address his retirement. Mike? Thanks, Mike, and good morning, everyone. Today, we announced 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.

Speaker 3

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 HBV. I continue to believe that Arbutus is on the correct path to developing a functional cure for the millions of patients living with HBV. 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 with the discovery and development of cifosbuvir, backbone of curative therapies for hepatitis C, which has already cured millions of patients globally.

Speaker 3

Learnings from the HCV story spurred me towards finding a cure for the more challenging problem, HBV. This led to the founding of Arbutus, where we have been able to build a world class team uniquely positioned to potentially transform the HBV treatment landscape with drug candidates like imduceran 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'm 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.

Speaker 3

Look forward to following the future successes as the company advances its mission in finding a cure for HBV. Thank you and back to Mike.

Speaker 2

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 HBV and driving value for our company. We believe our 2 proprietary clinical assets in HBV, Indusiran, our RNAi therapeutic and AV-one hundred and one, our oral small molecule PD L1 checkpoint inhibitor have the potential to deliver on our 3 pronged approach to functionally cure chronic HBV, which involves reducing surface antigen, suppressing HBV DNA and boosting the immune system.

Speaker 2

While imduceran has shown activity in all three of these I'll turn the call over to Karen shortly to walk through preliminary data from our Phase 1a1b clinical trial with AB101 and to provide an overview of our 3rd Phase 2a clinical trial that is evaluating the combination of indusiran and durvalumab, a PD L1 monoclonal antibody, which has begun screening patients. Currently, we have 2 Phase 2a combination clinical trials, the AB729,201 trial, which includes the addition of interferon and the AB729,202 trial, which includes the addition of Barentus Biotherapeutics Immunotherapeutic VTP-three hundred. 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 2 Phase 2a trials with imduceran, which could potentially include patients who achieve undetectable surface antigen. As we've previously stated, achieving undetectable surface antigen in either of these 2 Phase 2a clinical trials would be an important validation of imduceran's role as a cornerstone in potentially achieving a functional cure for patients with chronic HBV.

Speaker 2

We are happy to report that 2 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 AB-seven twenty nine-two zero three clinical trial and to discuss the AB-one hundred and one Phase 1 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 and A. Karen?

Speaker 4

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 HBV DNA and boosting the immune system. In our clinical trials conducted to date, imduceran has been shown reduce HBV DNA in untreated patients and reduce surface antigen when given both with and without ongoing standard of care Nuc therapy. In addition, evidence of HBV specific T cell reawakening has been observed in some patients undergoing treatment with imduceran. To further boost the immune system, we designed our Phase 2a trials to evaluate imbusiran in combination with 1 of 3 immunomodulatory approaches: interferon, a therapeutic vaccine or a checkpoint inhibitor targeting the PD-onePD L1 axis.

Speaker 4

Our 2 ongoing Phase IIa clinical trials, AB729-two zero one and AB729-two zero two are evaluating indusiran 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 EASL Congress in June. Note that we also amended the AB-seven twenty nine-two zero two trial to evaluate the addition of PD-one checkpoint inhibitor antibody nivolumab to the indusiran and VTP-three hundred 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 3rd Phase 2a clinical trial, AB729203, which is evaluating indusiran in combination with durvalumab, an anti PD L1 monoclonal antibody.

Speaker 4

While all of these Phase 2a trials are geared toward finding the right immune modulator to combine with adusiran, the AV729-two zero three trial with zirvelumab specifically intended to evaluate how we can use checkpoint inhibition in combination with imduceran to boost HBV specific immune responses. This trial will inform upcoming combinations with our proprietary oral small molecule PD L1 checkpoint inhibitor, AV-one hundred and one. With that backdrop, I'd like to provide more information regarding the AB729203 trial design. AB729203 is an open label, multicenter Phase 2a clinical trial evaluating the safety, tolerability, antiviral and HB specific immunologic activity of imdusiran and ongoing Duke therapy in combination with durvalumab, an approved anti PD L1 monoclonal antibody in patients with chronic hepatitis B. We intend to enroll 30 virologically suppressed patients into 3 separate cohorts.

Speaker 4

All patients will receive 60 milligrams of imdusiran every 8 weeks with their ongoing Duke therapy for 48 weeks and will receive 2 doses of durvalumab at prespecified times during the indusiran treatment period that will differ by cohort. After completion of treatment, all patients will be assessed for eligibility to discontinue Nuc 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 imbusiran treatment. Now moving on to our proprietary oral small molecule checkpoint inhibitor, AV-one hundred and one, that is differentiated from monoclonal antibodies such as durvalumab and nivolumab in the following ways based on our preclinical testing.

Speaker 4

1st, AB-one hundred and one is liver centric, meaning it preferentially traffic 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. 2nd, AB101 has typical small molecule pharmacokinetics and therefore a much shorter duration of effect than long acting antibodies, thus allowing for the potential to modify the dose or dosing interval to maximize effect or to stop dosing to quickly mitigate any safety concern. 3rd, AV101 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.

Speaker 4

It is for these reasons that we are excited about the potential AB101 in HBV and are advancing our AB101 clinical program, which is currently evaluating AB101 in a double blind, randomized, placebo controlled Phase IaIb clinical trial known as AB101001. This trial is designed to investigate the safety, tolerability, pharmacokinetics and pharmacodynamics of AB-one hundred and one. The trial consists of 3 parts, starting with single and multiple ascending doses in healthy subjects and culminating with multiple doses in patients with chronic HBV. In Part 1, which is the single ascending dose portion of the trial, we have enrolled 4 sequential cohorts of 8 healthy subjects each to date. Within a cohort, 6 subjects received AB101 and 2 subjects received placebo.

Speaker 4

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, 5 of the 6 subjects had test samples that were evaluable for receptor occupancy, and all 5 of these subjects showed evidence of PD L1 receptor occupancy between 50% 100%, indicating that AB101 is interacting with its intended target. 1 subject in this cohort was excluded from the PD evaluation as their samples cannot be analyzed. We are now in Part 2 of this trial, where cohorts of healthy subjects are receiving multiple ascending doses of AB101.

Speaker 4

Our goal is to move as quickly as possible into Part 3, 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 HBV specific immune tolerance and in T cell activation. And the addition of a checkpoint inhibitor in combination with imduceran could potentially further enhance HBV specific immune responses. With that, I'll turn the call over to Dave Hastings for a brief financial update.

Speaker 4

Dave?

Speaker 5

Thanks, Karen, and good morning, everybody. We ended the Q1 of 2024 with approximately $138,000,000 of cash, cash equivalents and investments compared to approximately $132,000,000 as of December 31, 2023. During the quarter ended March 31, 2024, we received $21,800,000 of net proceeds from the issuance of common shares under Arbutus' at the market offering program. These cash inflows were offset by $19,300,000 of cash used in operations. We still expect our 2024 net cash burn to range from between $63,000,000 to $67,000,000 excluding any proceeds from our ATM program.

Speaker 5

In April 2024, we received an additional 22 point $4,000,000 of net proceeds from sales under our ATM. And now importantly, we believe our cash runway is sufficient to fund our operations through the Q2 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 2

Thanks, Dave. With today's update, we have achieved most of our first half twenty twenty four key milestones, including reporting preliminary data from the AB101 1 Phase 1a1b clinical trial and initiating the Phase 2a clinical trial with imduciran and durvalumab. We look forward to reporting the data from the AB729-two zero one and 2 0 2 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 AB101001 trial. 2024 is off to a strong start and it wouldn't be possible without the dedication of Meyer Buda's colleagues.

Speaker 2

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 and 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 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.

Speaker 2

I refer you to the press release that we issued on April 4, which is available on our website and summarizes the claims related to the 3 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.

Speaker 2

The court has set April 21, 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.

Speaker 2

Operator, we're now ready to open the call for Q and A.

Operator

Thank you. At this time, we will conduct a question and answer session. Our first question comes from Dennis Ding with Jefferies. Please go ahead.

Speaker 6

Hi, good morning. Thanks for taking our questions. 2, if I may, on the pipeline. You guys have a few Phase II trials with a lot of different combinations going on. But how about anything we can get any functional pure signals?

Speaker 6

And is that a 2025 type of event? Or can we get some data later this year? And then number 2, I appreciate you started a new Phase 2 with dervo, but I'm just curious how much more data do you think you'll need from your hepatitis B trials before you can start a Phase 3? I'm just wondering what is the gating factor here? Is it waiting for AB101 to show some combo data or the data from the new derma study, which is essentially 1 year treatment and 1 year follow-up?

Speaker 6

Just wondering what the gating factor is there? Thank you.

Speaker 2

Good morning, Dennis. Thanks for the question. So Karen, do you want to handle Dennis' first question on functional cure? Functional cure, excuse me, yes, functional cure.

Speaker 4

Yes, sure, absolutely. So Dennis, as you know, these 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 6 months off of all treatment. So that is ongoing in both of our Phase 2 studies at the moment, both the 201 Interferon study and the 202 study in combination with Parenzys' VTP-three hundred. So as the data comes in and as we are able to compile that data into a meaningful data release with sufficient number of subjects, we'll certainly share that data when we can.

Speaker 4

So I can't give any additional guidance just to say that the trials are ongoing and we'll present the data as it becomes available.

Speaker 2

Okay. And then on to the second question was in regards to darolumab 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, So yes, we're starting a new trial and yes, we think that will be valuable and helping to inform how we think about the addition of AB-one hundred and one to indusiran. 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.

Speaker 2

As you know, the goal here is functional cure. 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 6

Got it. Thank you.

Speaker 4

Thanks, Dan.

Operator

One moment for our next question. Our next question comes from Ed Arce with ACHC Wainwright. Please go ahead.

Speaker 7

Hi, good morning, everyone. This is Thomas Yip 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 induciran, with the next Phase 2b or Phase 3 study, would that be expected to evaluate emtuziran as a monotherapy or in a combination or perhaps both?

Speaker 2

So Thomas, good morning. Thank you. 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 HBV. We have to hit those 3 pillars that we talk about frequently.

Speaker 2

So I think as we think about what a next study might look like, it's definitely going to be a combination study.

Speaker 7

Understood. Perhaps one question for Doctor. Sims for the new Phase 2a study with divalumab. Can you discuss the rationale behind different dosing interval for divalumab and what is the significance to analyze these different dosing intervals?

Speaker 4

Yes. Thanks for the question, Thomas. So the idea here is evaluating the extent of checkpoint inhibition that's necessary to try to induce that HBV specific immunity. So 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.

Speaker 4

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 access in the context of the surface antigen reduction that we see with induceiran. So that's the idea behind the trial. Is it best to inhibit checkpoint access during the acute decline of surface antigen? Is it best to inhibit after surface antigen has reached inator somewhere in between and doing that at multiple time points.

Speaker 4

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 7

Understood. Thank you. And perhaps one last question for AD101. After completing the multi ascending dose phase of the ongoing Phase 1 study, what's the next step for the program? Would that be looking at a combination study in HCV or are there other therapeutic areas that AD101 can have potential in?

Speaker 4

Sure. Yes. Thanks for the question. Again, just to clarify, so the current study is a 3 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.

Speaker 4

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 1 study, the next goal be to put it in combination with infusiran in a Phase 2 study as quickly as possible.

Speaker 7

Understood. Thank you again for taking all questions and looking forward to the EASL data readouts.

Speaker 2

You're welcome, Thomas. Thank you.

Operator

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

Speaker 8

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 AV-one hundred and one, it sounds like so far you've seen good safety data, but just would be curious if you're kind of thinking of 25 mgs as a cap in the MAD as well. And then are you when you're thinking about this the durvalumab trial, have you seen anything from the nivo combination so far that might be playing into your thinking on different timings?

Speaker 8

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 2

All right. So, Charlie, good morning. Thanks for the question. So Karen, why don't you handle the question with regards to AV-one hundred and one and the nivo lead to durvalumab question?

Speaker 4

Yes, sure. Absolutely. So the data we're sharing thus far is just the extent of dosing we've completed with AV-one hundred and one. 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 regimen.

Speaker 4

So 25 as reported today is the highest dose we tested with an excellent safety profile and good pharmacodynamic profile. So we'll be evaluating different dosing levels as we move on through trial. So 25 isn't necessarily a cap, it's just the data we have available to share with you today. So and in terms of the nivolumab data coming out of the 202 study, obviously, I can't comment on that. 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.

Speaker 4

So that data I can't comment on, but certainly we look at all of our trials holistically and certainly would, as Mike said earlier, move forward or adapt as we see the data emerging with our trials. But yes, to date, I can't vinovolumab arm and the 2 zero two study.

Speaker 2

And then Mike, do you want to handle the last question? Yes. On the ALPK1

Speaker 3

question, yes, we're aware of the an abstract just came out on EASL on that. Frankly, it just came out. So we are we're interested in looking at the abstract more fully and obviously seeing the presentation at EASL to get a full understanding of the target.

Speaker 8

Got you. Great. Thanks so much for the questions guys.

Speaker 2

Thanks, Charlie. Charlie.

Operator

One moment for our next question. Our next question comes from Rory Buchanan with Citizens JMP. Please go ahead.

Speaker 9

Thanks for taking the questions. Obviously, congrats to Mike Sofia on the planned retirement and I definitely miss his deep insights and observations on the calls. You have 8 months to get to a functional chair now. Yes, just a few questions. Just so I guess on the 203 trial, I think there's a typo in the slide that says Q48 weeks.

Speaker 9

And I think Karen said every 8 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 durvalumab dosing, there's no other the arm's all identical. So is that the only variable? There's no difference in actual dose levels or anything else?

Speaker 9

I guess that's my first.

Speaker 4

Yes. Thanks for the question. So you're absolutely right. The imbusiran dosing is 60 milligrams every 8 weeks as we have been studying throughout our Phase 2 program. So we'll go in and make sure that that's correct in the deck.

Speaker 4

But yes, 60 milligrams every 8 weeks of embusiran 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 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 2 jivolumab doses.

Speaker 9

Okay, great. And then follow-up on the 101 dosing question. So it's 25 mgs per day the dose you started Part 2 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 4

Right. So in regards to the dosing of AV-one hundred and one in Part 2 of the study, again, I can't comment on that. 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 9

Okay, great. And then the last one, maybe can't answer this either, but some of the nivo combo with Berensys vaccine. Can you give us a sense, it looks like the enrollment target went up by a couple of 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 4

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 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.

Speaker 4

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 9

Okay. Thank you.

Operator

Thank you. One moment for our next question. The next question comes from Keay Nakae with Chardan. Please go ahead.

Speaker 10

Yes. 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 3

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

Speaker 10

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

Speaker 3

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

Speaker 10

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

Speaker 4

So it's a total dose duration of 7 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 it could be a daily dose, it could be every other day, every 3rd day, 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 7 day maximum duration.

Speaker 10

Okay. And when do you expect to be able to advance into Part 3 of the study?

Speaker 4

Right. So it really depends on how these multiple ascending dose arms proceed in the healthy subjects. So really we just need sufficient again, safety PK and PE data to feel confident to move into that third portion of the trial and to choose a dose to initiate that part of trial that we think will have impact in these chronic hepatitis B subjects. So again, it just depends on the progression of Part 2 of the study. But it is, as we've said earlier, an integrated protocol.

Speaker 4

So the Part 3 of the study is already approved and we would be able to move on as soon as we are ready with the data.

Speaker 10

Okay. Thanks.

Operator

Thank you. I'm showing no further questions at this time. I'd now like to turn it back to management for closing remarks.

Speaker 2

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 HBV assets. Operator, that concludes our call.

Operator

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

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Key Takeaways

  • Co-founder and Chief Scientific Officer Dr. Mike Sofia announced he will retire at the end of 2024 but will continue in his full capacity until then.
  • Arbutus is advancing a 3-pronged approach to achieve a functional cure for chronic HBV with two proprietary assets: indusiran (RNAi therapeutic) and AB101 (oral PD-L1 checkpoint inhibitor).
  • Two Phase 2a trials of indusiran combinations will report end-of-treatment data at the EASL Congress in June, a third trial with durvalumab has begun screening, and Phase 1a/b data for AB101 shows dose-dependent PD-L1 receptor occupancy with multiple-ascending dose results expected in H2 2024.
  • At March 31, 2024, Arbutus held approximately $138 million in cash and investments, expects a 2024 net burn of $63–67 million, and has a cash runway through Q2 2026.
  • A recent Markman ruling largely sided with Arbutus on key patent terms in the Moderna litigation, with trial set for April 2025, and Arbutus continues to defend its LNP delivery technology patents.
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