Arcturus Therapeutics Holdings Inc.

and the rest of the world. and our ARCT 032 study from Turkey and Israel respectively. Clinical execution remains on schedule and we are laser focused on generating the data needed to support the phase three decision expected in Q4, 2026. Turning to our OTC deficiency program, ARCT 810. During the quarter, we completed enrollment of the ongoing phase two study and all enrolled subjects completed study drug dosing. This is an important operational milestone and allows us to now focus on evaluating the supplementary data generated from the enrolled study population. We remain grateful for the continuing support, ongoing encouragement, and strong engagement on behalf of our ARCT 810 OTC deficiency study by the patients, their families, and the rare disease care community. Thank you for all your collective help and interest in our development program. Our current efforts are focused on data review, preparation for upcoming regulatory interactions, and planning for an end-to-phase two meeting regarding the path forward across both adult and pediatric development. We expect to communicate both the data and regulatory plan for OTC deficiency program in Q3, 2026. Across both our rare disease programs, our focus remains on disciplined clinical execution High Quality Data Generation, and Productive Regulatory Engagement to Support Efficient Development Decisions. With that, I will turn the call over to Dennis.

Thanks, Alan, and good afternoon, everyone. Our press release issued earlier today includes financial statements for the three and six months ended June 30, 2026, and provides a summary and analysis of year-over-year performance. Please also reference our Form 10-Q for more details on our financial performance. Cash and cash equivalents were $191.5 million as of June 30, 2026 and $230.8 million on December 31, 2025 for a decrease of $39.3 million over the first half of 2026. Revenue was $3 million and $5 million for the three and six months ended June 30, 2026, compared to $28.3 million and $57.7 million in the comparable periods last year. Lower revenue was recognized under the CSL collaboration as our tourists progressed towards termination of the agreement and regaining rights to co-stave and its broader infectious disease vaccine portfolio. Research and development expenses were $17.5 million and $39 million for the three and six months ended June 30, 2026, compared with $29.6 million and $64.5 million for the corresponding periods in 2025. The decreases were primarily driven by lower research and development spending, including reduced Salaries, wages, benefits, and facilities costs as the company continues to advance its CF and OTC programs while maintaining its disciplined approach to capital allocation. General and administrative expenses were $11 million and $20.5 million for the three and six months ended June 30, 2026, compared with $10.3 million and $21.7 million in the comparable periods last year. Overall, general and administrative expenses remained relatively consistent across periods with a slight quarter to quarter increase due to legal fees partially offset by reduced spending in salaries, wages, benefits and facilities costs. We remain focused on disciplined execution and capital allocation as we advance our rare disease programs. The CSL Securus Termination and Settlement Agreement strengthens our financial position as we regain control of those assets, and the Thermo Fisher collaboration funds and supports the execution of late-stage development of our CF program. We continue to maintain a strong balance sheet and cash runway of over two and a half years through year-end 2028, allowing the company to reach import-critical and regulatory milestones for its rare disease pipeline. With that, I'll pass the call back to Joe.

Thank you, Dennis. Arcturus continues to execute across our rare disease therapeutics portfolio while strengthening the long-term strategic position of the company. With enrollment progressing in our phase two ARCTO32 study and completion of enrollment and dosing of ARCT810 and the return of strategic control of our vaccine portfolio, We remain focused on advancing important clinical, regulatory, and corporate milestones through the remainder of 2026. And with that, let's turn the call over to the operator for questions.

Thank you. If you'd like to ask a question, press star 1 on your keypad. To leave the queue at any time, press star 2. Once again, that is star 1 to ask a question. And we'll take our first question from Lily Nosongo with Lyric Partners. Please go ahead. Your line is now open.

Hi, good afternoon. Thank you for the update on the quarter. Just thinking about the OTC program, could you maybe provide us a little bit of detail in an overview of the data we should expect at the upcoming readouts later this quarter? Would it be solely the U.S. pediatric, U.S. adolescent and adult patient, or would we also see a longer-term update from the European patients?

Hi, Lily, and thanks for the question. Yeah, with dosing completed, you're right, we are preparing for this data disclosure later this quarter. We're evaluating the Phase II clinical data, which includes the U.S. and European data set. The new data, of course, will be the most recent patients that have added and completed dosing here in the United States. But it will also include supplementary data that was requested by the FDA in the Type C meeting earlier this year. and so we just intend to share a fulsome update on the OTC program that includes not only the Phase 2 data but the requested Type C data and providing additional detail with respect to the regulatory path forward.

I'll leave it at that.

Great, thank you. Maybe as a follow-up, still staying with OTC, Do you view diet liberalization as the bar for success, or should we be looking maybe at the biomarker level?

With respect to biomarker levels, yes. Well, I know the biomarkers being evaluated and measured are ammonia and glutamine and, of course, urea itself. But maybe, Alan, you can comment or... address the rest of the question.

Yeah, great question. I think that the two elements that are going to be most important are not just the biomarkers, they're certainly important because it speaks to mode of action, but also how these patients feel as well as function. So it'll be the totality of the data that we've been able to generate up to this point, not only relating to safety and tolerability, but also biomarkers, as Joe just mentioned, most notably the Ammonia levels and glutamine, but also the additional quality of life and functional measures that we're collecting. So, it really will be the totality of all the data is what the agency is interested in wanting to see and which is obviously important to move our program forward.

Thank you.

Thank you. We'll take our next question from Pete Staropoulos with Cantor Fitzgerald. Please go ahead. Your line is now open.

Yeah, thank you very much. Hi, Joe and team. Congrats on the progress. I have a couple of questions on the CF program. First one is, you know, how has the cadence of enrollment been? And will you wait for all the patients to complete the study before data disclosure? Or is there a possibility of an interim look? And are there plans to adjust the protocol to allow dosing past 12 weeks or three months?

Okay, there's a few questions there, but thanks, Pete, for joining the call. With respect to the cadence of enrollment, we touched on that we've expanded our footprint to ex-US sites in Israel and Turkey that are assisting with that challenge with all rare disease programs. It's all about the cadence of enrollment, and we feel confident. In fact, we've expressed considerable or high level of confidence with respect to the cadence of enrollment rate now that Israel and Turkey are participating in this trial. With respect to the remainder of the questions, I can turn the time over to Alan.

Sure. I think, Pete, the essence of what you're asking is, when do we know that we can draw a line and total up the cumulative nature of the data we've generated and that we're satisfied that it's sufficient to make a decision? I think the data is going to drive that, but certainly we believe that at the rate we're currently enrolling, and the quality and nature of the data that we're generating, particularly now that we've added Israel and Turkey to the mix, which have such a larger preponderance of the patients we're most interested in identifying and enrolling. We believe that the time should be sufficient through balance of Q4 to be able to accumulate the necessary data to make an informed decision on what's best for the program and for these patients moving forward.

And just to add to that, if you notice, our new guidance is focusing on the decision to proceed rather than a data share or completion of enrollment. And this is simply because the next meaningful event for this program is that decision, which is guided for Q4. The decision to proceed triggers significant and meaningful contributions from Thermo and our recent deal that we announced. and so that's what we're focused on is getting sufficient data for that decision to proceed in Q4.

All right, thank you for that. I do have one question on LCI. It's being used for CF, the Phase II study. Can you just talk a little bit about this test, you know, sort of how sensitive is it and how variable is one close reading to another?

Yeah, LCI is definitely a different lung function measurement. Alan, maybe you can comment on some key differences there with sensitivity, et cetera.

Yeah, sure. I think the biggest unknown and the biggest challenge for using Lung Clearance Index in adults with CF has been the lack, as you know, of normative data among the population that's of most interest to us. Fortunately, as you're probably aware, the CF Foundation's funding, the REACH study, and that study is, we're going to get an update on that at the upcoming cystic fibrosis meeting in Atlanta in October. And the foundation has been kind enough to offer to make that data available, especially for companies like ours and others that are working in this space so that we can have access to that data and use it as a natural control. So the short answer is, is that the sicker that patients are performing this test, the more challenging it is, but we're focusing in on a mix of patients within a range that we believe we should be able to get highly reproducible, meaningful data that's not only reproducible but also is giving us a much more sensitive measure of changes in the smallest airways where the earliest changes of lung disease occur in this population. So it's adding additional nuanced information that spirometry and pulmonary function testing traditionally doesn't give us. So we think it's actually better for the patient population. It's better for our understanding of the disease itself. And we think it might lead to another pathway forward for showing an ability to stabilize and improve lung function in this very vulnerable patient population.

All right. Thank you very much for that, Calder. And congrats once again on the quarter.

Thank you. Thanks, Peter.

Thank you. We'll take our next question from Yanan Vu with Wells Fargo. Please go ahead. Your line is now open.

Hi. Thanks for taking our question. This is Kuan Yang for Yanan, and congrats on the quarter. So on the CF program, can you share by 4Q what kind of data set do you expect to have collected to help you make a decision? And given that this is an open-label study, are you seeing the data in real time? Any safety update you can give us? Thank you.

Yeah, the data we're collecting is FEB and LCI data for pulmonary lung function data, and that's supplemented with high-res CT scan data and validated quality of life measures and surveys. So that's going to be the collective data that's going to be under consideration when Arcturus makes its decision to proceed. And then with respect to the open label nature of the study, absolutely. It's an open label study, so and Arcturus and the team will have access to data on an ongoing basis.

Also, any safety signal you have observed or any comments on that? Thank you.

Yeah, with respect to CF safety, the ARCTO32 is the name of our CF candidate and this This candidate, or ARCTO32, has been in over 50 participants to date, ranging from all the way up to 15 milligrams for 28 days of daily dosing. And we've done so without steroid treatment before, during, or after. And this whole time being permitted by regulatory agencies to self-administer in their home, not necessarily required for these people to do so in a clinic. And we're presently active in a 12-week study So this is, I guess, a longer way of saying that we have a high level of confidence in our safety and tolerability of this platform, given the dose levels and the duration we've collected so far. And we hope that that continues. But it is a key differentiator for our program. So thank you for the question. You know, it's been decades of failures of inhaled therapeutics, and it's always been attributed to failures in toxicology and tolerability. Humans just don't like to inhale foreign substances, so we've overcome those challenges over the last decade of R&D.

Got it. And a quick question on OTCD. Has the EOP2 meeting with FDA been scheduled, and what are the potential outcomes from the meeting? Thank you.

Yeah, we've already highlighted and guided that we're going to have a fulsome data and regulatory path update later this quarter, and that'll be the opportunity to provide some more details about that EOP2 meeting. And so that will be the appropriate time to do so. Got it.

Thank you for all the callers.

Thanks for your questions.

Thank you. We'll take our next question from Yajal Nakomovic with Citigroup. Please go ahead. Your line is now open.

and Joanne Kim on for your goals. Thanks so much for taking our questions. Just curious, but I'd love to hear a little bit more about the collab with Thermo. Can you tell us a little bit about how that came about and have they seen any interim phase two data or 15 milligram data ahead of you guys making that deal?

Yeah, it's a great question. So, there was Significant interest from multiple large manufacturers in the CF product because it's a very unique product. Unlike our vaccine, our co-stay vaccine that we just regained rights and control, that vaccine is dosed at five micrograms once a year. It's a very infrequent, long-duration acting product. Unlike that product, the CF product is 10,000 micrograms daily. So because it's a significant commercial manufacturing deal, then you can understand the level of competitive interest from large manufacturers. So as they came together, we put forward a deal that made sense to all parties involved, and Thermo Fisher ultimately became our exclusive partner for commercial manufacturing of the CF product through that path. Did I address your question?

Did they happen to see the internal phase 2 data?

Yes, absolutely. Just like in all major deals, and this one was a significant one for us, they went under CDA, they have access to an e-room and all the clinical data, and understanding it's an open-label study. So yes, they had access to all the data.

Got it. Thanks very much.

Thank you. We'll take our next question from Myles Minter with William Blair. Please go ahead. Your line is now open.

Hi. This is Jay Gon from Myles. Thanks so much for taking our questions. One on OTC. Just wanted to get a sense of the baseline hyperammonemic crisis rate in the Phase II study and how that might compare to other OTC trials to date. And then one on CoState. You mentioned that the regulatory path for co-stave approval in the U.S. is clear. Just wanted to maybe get a little more color on what that path is. Thanks.

Sure. So, do you want to take that question, Alan? Yeah.

So, for our current ongoing OTC program, we're giving five doses over approximately a 12-week period of time. So, the anticipated percent and burden of exacerbations or hyper anemic episodes occurring during that window and the nature of our inclusion and exclusion criteria are really not looking to capture patients that are unstable enough that we would likely be capturing those events or looking to those events to be helpful and informative during the course of just a simple five dose regimen. What we're really our goal and objective here was to bring in patients who are on a stable protein intake, who are stable medically and functionally, but who still are burdened with OTC deficiency and are adults. The goal there being that we want to see if we can have an impact on their baseline periods of urogenesis as related to measurements of blood ammonia and glutamine levels, as well as other trace minerals. So the short answer is that we aren't actively looking for patients who are labile enough for which to capture those events, but obviously in longer-term studies where we would be treating patients more chronically, and in particular in a pediatric population where the burden is much more problematic and the reason for our program is to want to direct towards newborns and young children who are much more vulnerable and sicker, that would clearly be a greater level of interest and focus for and other subsequent studies that we hope to be getting into in the near future.

Does that address your question?

Yeah, and then I just wanted to ask about CoStave and the potential development in the U.S. that you referred to.

Oh, and yes, we already received, you know, we had very regular interactions with the United States FDA for several years And then under the new administration here in the United States, there was an abrupt change in view of vaccine policy. And however, even under that new administration, we received very clear guidance as to what is needed for us to get this approved in the U.S. So what I'm communicating is that we have a very clear path of what's required, what's remaining to do to get this approved in the U.S.

Thanks, Jake.

Thank you. We'll take our next question from Whitney Isham with Conaccord Genuity. Please go ahead. Your line is now open.

Hey, guys. Just wanted to quickly on CF follow up. I appreciate we're not going to necessarily see a data update in the fourth quarter, but as you announced, whether or not you're moving forward into a phase three can you help us understand how you're thinking about like more quantitatively which endpoints are of importance and what you're looking for and I guess is there a scenario where maybe you're not seeing an FEV benefit but you might still move forward based on something you're seeing on LCI, CT, etc. Thanks.

Yeah I'll begin and then provide Alan some time here too. So just to refresh we are collecting FEV, LCI data, high-res CT scan data and quality of What is very unique in this process is as we've engaged the FDA, we have come to realize that our technology and our product and the patients that we're pursuing are very, very unique. We're the first to do this. So in terms of what thresholds of success need to be achieved is going to be set and established by us in this process, not by historical or other and many more precedences in the field. And so what we've heard consistently is anything positive with respect to the data that we're collecting would be very well received and a significant win and exciting for the Class 1 CF community. There will be increased emphasis on lung function measurements, of course, like FEV and LCI. But, Alan, anything to add?

Yeah. Joe got the essence of what I'm thinking and wanted to get across. But just to reframe, remember that this population of class one mutation patients, particularly those who are adolescent and young adults, are on average experiencing anywhere from one to over 2% drops in their percent predicted FEV1 just as a course of surviving annually. So just being around and doing a good job of taking care of themselves The burden of this disease is remarkable, and it's consistently diminishing their baseline lung function day after day, year after year. So the goal here is to see if we can stabilize and improve these patients, and it's probably going to be a measure of not just a single spirometric measure or a single change in LCI. Stabilizing this would clearly be a big step forward for these patients, also how they feel and function. Additionally, their quality of life measures, how they're able to maintain themselves, and their overall health and well-being will all be in the mix of the elements that we're going to be looking at to help inform us on next steps for the program.

Got it. That's helpful. And then just one follow-up clarification on CoastAid. In Japan, given the change in the CSL relationship, how should we think about impact there? Sorry if I missed it. Thanks.

Well, it's a great question. We were splitting the profit share three ways, and now that's no longer. It'll be split two ways. But those conversations are very active right now with Meiji. We have a great relationship with them in Japan. We are definitely preparing for the upcoming Thank you. Yeah.

Thank you. We'll take our next question from Adam Dahlwood with the Riley Securities. Please go ahead. Your line is now open.

Hey, guys. This is Adam on for Mike.

Thanks for taking the question. So just curious whether you've given any thought to the fact that since Vertex required, I think it was a four-week bronchodilator and clinic-supervised dosing while ARCT32 is dosed at home.

How are you thinking about that tolerability gap as a durable differentiator?

and what do you think could apply for the phase three?

Thanks. No, I appreciate the question. It gives us the opportunity to provide more detail as to why we're observing a more attractive safety and tolerability profile with this platform. So the first point of key differentiation is the lipid nanoparticle is different. It's chemically different. Instead of a carbon-based core, it's a thiocarbamate core, which means there's sulfur, oxygen, nitrogen. These heteroatoms provide And it's also chemically different how it interacts with the biology in the body too. So we have a different lipid nanoparticle that's biodegradable, non-accumulating, and that is very important with respect to safety and tolerability. The second point of differentiation is that our manufacturing process to purify the mRNA is different. We have trade secret know-how and IP around the process to purify the mRNA molecule itself. And the impurities coming out of the output of this manufacturing process can be very problematic with respect to undesired inflammatory and immune responses. So controlling those is a very important differentiator that uses our technology. And the third point of differentiation is our nebulizer. This aerosolization of these particles It was proven to be very challenging in the early days of this program. We spent a few years and we had support from the CF Foundation to optimize the nebulizers so that it retains the integrity of the particle through the aerosolization process. And you don't want these particles aggregating and forming macro particles during the inhalation process. So we've optimized against that. So whether it's the lipid nanoparticle or a more pure mRNA, or an optimized nebulizer. If you take all that three together, that contributes to the better safety and tolerability profile.

Okay, great. Yeah, very helpful. Thanks a lot. Thank you.

Thank you. We'll take our next question from Adam Walsh with Roth Capital Partners. Please go ahead. Your line is now open.

Hi, thanks for taking my questions. So you announced cohort four began dosing in March of 2026. And I think by my math, we're about five months out. Joe, you've spoken to the safety and tolerability advantages with 032. And I'm just curious, is kind of the lack of any disclosure on tolerability at this point something that we can read into and continue following? or are we getting over our skis with that?

No, I appreciate the question. It does seem logical. I think it's a safe statement that if there is anything serious or severe that's occurred in our trial or material, we would have to disclose that. But with respect to commenting on details, with respect to safety and tolerability, we will wait for the appropriate time to do so, like we've done with the previous cohorts. Alan, anything to add there?

Yeah, I think we're trying to be thoughtful in terms of our sharing of information. And rather than parse through it because we have the position to have the data presenting itself in an open label manner throughout, it's really going to be the cumulative experience with as many exposures as possible, ideally through three months and upwards to 20 patients. That's really going to be the determinant as to next steps. So we'd rather wait until we have a larger body of data over more patients over a longer period of time to make a point of sharing what we believe is the totality of our experience thus far beyond 28 days. And we look forward to sharing that in the months ahead.

Yeah.

That's really helpful, Collar. Thank you.

Thank you. We'll take our next question from Jenny Kim with VTIG. Please go ahead. Your line is now open.

Good afternoon. Thank you for taking my question. This is Jenny on for Tom Schrader. So with the global vaccine rights returned to you, you're effectively running a standalone vaccine portfolio on top of two active rare disease programs. How are you thinking about the cost to maintain and monetize CoSafe and the broader infectious disease portfolio, and does retaining these rights change your R&D expense trajectory meaningfully?

Let me restate your question to make sure I get the crux of it. Is it good news that we've regained rights and control? Absolutely. And I think your question is like, well, how are you going to pay for all of the exciting applications of this platform? And there's two efforts that we're going to be focusing on now that we have control. Number one is commercialization. We'd like to continue to mature the product that's already partnered with Meiji as a distributor in Japan and support them in what we can in Japan. and then now we can more proactively with the focused commercial efforts even as a small company Arcturus to see if we can explore opportunities in Europe especially with the United Kingdom that's a that's an exciting potential opportunity there so there's commercial activities that will expand and if we're successful in any way there then those will pay for the other platform activities And then the other more potentially more obvious one is we now having control of this validated platform from a business development perspective that opens pathways to partnership and what that looks like and what opportunities there can be. There's a variety of opportunities. We've talked about CoStave, but also the vaccine portfolio includes really high value targets like seasonal flu and pandemic flu. EBV is an interesting target, HMPV, we have RSV. There's several, there's a long list of antibacterial vaccine opportunities that can be investigated with this platform, and the list goes on and on. So we'll be spending considerable effort in looking at partnering pathways now that we've regained control of the platform.

Great, thank you.

Thank you.

Thank you. We'll take our next question from Yael Jen with Laidlaw and Company. Please go ahead. Your line is now open.

Thanks for taking the questions and congrats on all the progress. I do want to continue the previous question in terms of this vaccine portfolio. Just curious, besides COSMA, What the clinical stage of other vaccine has been, both of flu as well as RSV and the EBV? Can I have a follow up?

Most of the data that we've collected has been undisclosed. Many of it has been preclinical. We have completed a phase one trial for seasonal flu influenza and pandemic flu as well. On that note, since you asked the question, I'm going to refer to my notes that I put together here before the call. But the phase one clinical study for the pandemic flu program, ARCT 2304, the phase one clinical study is completed and the grant with BARDA is fully executed. The manuscript with the results of the study with BARDA and the U.S. government has been accepted by Nature Communications. So we look for a publication there shortly. and Arcturus is planning to pursue scientific advice with EMA regarding a pathway to licensure later this year, probably in Q4. So those are two more active prominent clinical programs, seasonal flu and pandemic flu. With respect to the other programs, we didn't do any formal disclosures on that. We will likely do those under CDA with potential interested parties later this year.

Okay, great. No problem. And maybe just along that line, in terms of Meiji, if they choose to develop COVID vaccine for the next season, not the current season, but potentially next season, would that be something you guys also will get involved? Or how should we see that?

Well, yeah, we're always going to support Meiji in any way that we can. And then if If we have any future strategic relationships that can complement or help them, that would be something that we'd seriously consider. But the short answer is yes, we will help Meiji in any way possible, especially on the manufacturing and making sure that we're timely with respect to delivery of any materials that they need, etc.

Okay, great. Thanks a lot and congrats on the progress.

Yeah, thanks, Yale.

Thank you. At this time, we've reached our time for allotted questions. I will now turn the call back over to Joe Payne for closing remarks.

Hey, thanks everyone for participating on the call. Don't hesitate to reach out to our team for any remaining questions, and we'll get back to you as soon as we can. Bye for now.

Thank you. This brings us to the end of today's meeting. We appreciate your time and participation. You may now disconnect.