Ladies and gentlemen, thank you for standing by. Welcome to Atea Pharmaceuticals' first quarter 2026 earnings conference call. At this time, all participants are in a listen-only mode. A brief question and answer session will follow the formal presentation. If you should require operator assistance during the conference, please press star zero on your telephone keypad. I will now turn it over to the Atea management team. Please go ahead.

Hi. Thank you, operator. Good afternoon, everyone, and welcome to Atea Pharmaceuticals' first quarter 2026 Financial Results and Business Update Conference Call. Earlier today, we issued a press release which outlines the topics we plan to discuss. You can access the press release as well as the slides that we'll be reviewing today by visiting the Investor section of our website at ir.ateapharma.com. With me today from Atea are our Chief Executive Officer and Founder, Dr. Jean-Pierre Semodosi, Chief Development Officer, Dr. Janet Hammond, Chief Commercial Officer, John Vavrica, Chief Medical Officer, Dr. Arantahorga, and Chief Financial Officer and Executive Vice President of Legal, Andrea Corcoran, who will all be available for the Q&A portion of today's call. Before we begin the call, and as outlined on slide two, I would like to remind you that today's discussion will contain forward-looking statements that involve risk and uncertainties. These risks and uncertainties are outlined in today's press release and in the company's recent filings with the Securities and Exchange Commission, which we encourage you to read. Our actual results may differ materially from what is discussed on today's call. With that, I'll now turn the call over to Jean-Pierre.

Thank you, Jonay. Good afternoon, everyone, and thank you for joining us. I will begin on slide three. With two pivotal phase three top-line readouts for our global phase three HCV program ahead of us, 2026 will be a catalyst rich year for Eptaean. We remain on track and are very encouraged by the substantial progress our team continues to achieve. We completed patient enrollment for CBR, our North American trial, late last year with over 880 patients who are representative of the genotypes and demographics in North America. For C4, our ex-North American trial, I'm pleased to share today that we have completed enrollment for 95% of the cirrhotic and non-cirrhotic patients and anticipate to complete enrollment next month's schedule. Currently, enrollment is only open to the less prevalent genotypes, such as four, five, and six, which will a broad label. This set up two important phase three milestone. We expect top-line data from CBR in mid-year, as we have reported before, and top-line data from C forward around year end. Late last year, we expanded our antiviral hepatitis pipeline to address a major and medical need for immunocompromised patients living with chronic hepatitis E infection, a liver disease for which there is currently no approved therapy. If left untreated in this at-risk population, it can rapidly progress to cirrhosis within only three to five years. We have completed CTA-enabling studies for AT587, our lead product candidate, and we anticipate to initiate a first-in-human study mid-year. Initial results were presented in February at COI 2026, and additional data will be presented at ESO later this month to support AT587 as a potential first-in-class inhibitor against hepatitis E infection. I will review this exciting program and our clinical plan for a first in human study later in this presentation. Importantly, with $256 million of cash, cash equivalent and marketable securities as of March 31st, 2026, financial position to execute and complete our Phase III HCV program and advance our new HEV development program. We anticipate our casual runway remaining through 2027. With that, I will now turn the call over to Janet to review the profile. Thanks, Jean-Pierre.

On slide 5, we are conducting the first active-controlled Phase III global program for hepatitis C, comparing our regimen against the current standard of care, the Fospovir and Belpatisvir, which is marketed as Epclusa. The data generated to date for the regimen of Benifospovir and Ruzesvir support a differentiated, potentially best-in-class profile, combining high efficacy, short treatment duration, with a low risk for drug-drug interactions, dosing convenience, and no food effect. We continue to add to our data set, and recent results demonstrate a low risk for drug-drug interactions with proton pump inhibitors, which are taken by estimated at least 35% of hepatitis C patients. We've also confirmed the absence of an interaction with HMG-CoA reductase inhibitors, or statins, another important and commonly prescribed class of medications. In closing, I'm also pleased to share that we will be presenting additional results at EASIL later this month that support the potential for a best-in-class profile for our regimen. I'm going to hand the call over now to Arantxa to review our Phase 3 program for the treatment of hepatitis C. Arantxa? Thank you, Janet.

Moving ahead to slide 7, as a reminder, CBYOND enrolled patients in the U.S. and Canada, and C-FORWARD is enrolling patients in 17 countries outside of North America. Combined, we expect to enroll more than 1,760 patients in our Phase III program. Both trials are open-labeled, randomized one-to-one against the active comparator, and stratified by cirrhosis status and genotype, including patients co-infected with HIV. In patients without cirrhosis, treatment duration is eight weeks with benifosphorid and 12 weeks with the standard of care. Patients with compensated cirrhosis receive 12 weeks of treatment with either regimen. The primary endpoint for both studies is sustained viral response or cure 24 weeks after treatment initiation. Slide 8 shows that the geographic footprint of our global Phase III program was comprised of approximately 120 clinical sites in the U.S. and Canada for C-Beyond and another 120 clinical sites in 17 countries outside of North America for C-Forward. We completed patient enrollment of our C-Beyond trial in December with more than 880 patients, and we anticipate top-line results midyear. C-Forward has a broader global geographic and genotypic footprint, and we expect to complete enrollment midyear and to report top-line results around year end. As JP mentioned earlier, we are pleased to share that for C-Forward, we have completed enrollment of 95% of the trials in serrotic and non-serrotic patients. Enrollment is only open to the less frequent genotypes, such as 4, 5, and 6, which will support a broad label. Enrollment of C-Forward remains on track to be completed by midyear. On slide 9, let's review the phase 3 endpoint's patient population and data analysis for our global Phase III program. In C-Beyond, the primary endpoint will be analyzed in a modified intent-to-treat or MITT population as preferred by the USFBA. The analysis will include patients that have been randomized and those regardless of drug adherence or loss to follow-up. The statistical analysis will be based on an imputation model with success or failure depending on PCR value, whether negative or not, prior to patient treatment discontinuation. A key secondary endpoint will be the SBR rate in the per-protocol population. In C-Forward, the per-protocol population will be analyzed as the primary endpoint, as preferred by the EMA. And the SBR rate will only include patients who are at least 80% adherent as measured by pill count and have an SDR assessment at week 24. A key secondary endpoint will be the SDR rate in the MITT population. The same methods for assessing non-inferiority will be conducted in both phase 3 studies and in both patient populations. The phase 3 studies are powered 90% with 5% non-inferiority margin with expected rates above 95% in a modified intent-to-treat or MITT population. Using these two approaches in a post hoc analysis of the phase two results, the SDR rate was 95% in MITT population and 95% in the per-protocol population. I will now hand the call over to John Fabrica, our Chief Commercial Officer.

Thank you, Arantxa. I'll begin on slide 11. HCV remains a significant global healthcare crisis with an increasing incidence of infections despite the availability of direct IVRs for the past decade. Currently in the U.S., out of a reported 160,000 new chronic infections, only approximately 85,000 patients are treated annually. In the U.S., it's estimated that up to 4 million people are infected with HCV. The unrelenting high rate of new chronic HCV infections, which continues to outpace the number of patients being treated, underscores the need for a new differentiated and optimized therapy. Most countries worldwide, including the U.S., are not on track to achieve the World Health Organization's goal of HCV elimination by 2030. In fact, current estimates suggest we may not even achieve this goal by 2050. HCV is also a leading driver of liver-related morbidity in the U.S., including progression to cirrhosis and liver cancer, reinforcing the importance of expanding diagnosis and Moving to slide 12, the U.S. HCV market remains substantial with approximately 1.5% billion in annual net sales, about 50% of the roughly $2.6 billion global market, reflecting the size of the opportunity. In our discussions with healthcare providers, we consistently hear that a point-of-care test-and-treat approach, where testing, diagnosis, and treatment initiation occur in a single setting, can significantly reduce delays in care and minimize patient drop-off before treatment begins. This model has broad support, including from the CDC, and is gaining momentum through bipartisan efforts to achieve HCV elimination in the U.S. Key opinion leaders believe it can be an important lever to help increase the number of patients treated and support HCV elimination efforts, And they continue to emphasize the need for therapy designed to integrate smoothly into this care pathway. Let's turn to slide 13. This slide summarizes the U.S. ACV payer mix and expected access dynamics. Medicaid represents just over half of DAA volume, with Medicare and commercial plans accounting for the balance. On the right, payer research shows a favorable outlook for parity access and parity net pricing across all three segments with meaningful concentrations of Medicare, Medicaid, and commercial payers indicating they would be very likely to add another option. Overall, these data support our view that BEM or ZR could achieve broad formulary inclusion subject to regulatory approval. Slide 14. This slide highlights the competitive positions for the U.S. HCV market today. You can see that Inclusa and Mavirat drive value from different payer mixes. Inclusa is skewing more heavily towards Medicare, but Mavirat is concentrated in Medicaid. Let's move to slide 15. Using our phase two results, IQVIA conducted an independent quantitative market research study with 153 U.S. high prescribers. These physicians indicated that they would likely prescribe BAMRZERA regimen to approximately half of their patients, and the results were similar for all patients, regardless of their cirrhosis state. On slide 8, based on the U.S. HCD market dynamics, we believe we can be well-positions for a capital-efficient commercial launch. The prescriber base is highly concentrated, roughly 7,800 physicians, right about 80% of all DAA prescriptions. We can reach the vast majority of the market with a specialty sales force of approximately 75, including sales representatives, sales management, and medical science DAA zones. With no other candidates in late-stage clinical development, MRZR enters the market primarily served by only two regimens. On the supply side, all components and processes for large-scale manufacturing are in place, and the commercial launch supply production is already underway with a low cost of goods relative to expected net pricing. The four-week dosing blister card packaging supports patient convenience and adherence. Taken together, we believe the concentrated prescriber base, focused commercial infrastructure, and favorable manufacturing economics, position us for a short time of profitability following NDA approval. I will now hand the call back to Jean-Pierre to review the HEV program.

Let's move to slide 18. Hepatitis E virus, or HEV, is an acute and a chronic liver disease. In developing countries, genotypes 1 and 2 are most prevalent, and the virus is transmitted primarily through contaminated water, leading to epidemics of acute, self-limiting viral hepatitis. In developed countries, and mostly U.S. and Europe, genotype 3 is the most transmitted through contaminated food, such as undercooked meat. Genotype can cause chronic hepatitis in immunocompromised patients, which can progress to cirrhosis within a short time of three to five years. And as you may know, this has done what's occurred with hepatitis C or hepatitis B, where it takes 15 to 20 years or even longer. Moving to slide 19, in recent years, with the increasing number of patients who are immunocompromised, including solid organ transplant recipients, hematopoietic stem cell transplant recipients, as well as patients with hematologic malignancies, such as multiple myeloma, there a growing incidence of chronic hepatitis C infection in the U.S. and Europe. Currently, the standard of care includes reducing immunosuppression and off-label REBAV administration, which both present challenges leading to a real opportunity for an effective direct anti-viral drug. On slide 20, each year in U.S. and Europe, 3% of approximately 450,000 patients who have this underlying medical condition are at risk to develop chronic hepatitis E. The unmet need for this patient population potentially will present a market opportunity between $750 million to $1 billion each year. On slide 21, this slide highlights the preclinical data for AT587 as a potential first-in-class direct-acting antiviral for chronic hepatitis E. In the genotype 3 replicant in vitro model, AT587 demonstrates the greatest potency. And importantly, this antiviral activity has also been confirmed in primary human hepatocytes, the target organ for hepatitis E replications. In vitro data also indicates low potential for drug-drug interaction, which is important for this immunocompromised patient who, for some, take lifelong therapies. 22, today 587, as a clean in vitro and in vivo safety profile, CTA enabling GLP toxicology and safety pharmacology studies are completed, allowing us to advance to phase one studies and positioning this product candidate as a first in class direct acting antiviral for chronic hepatitis C infections. On slide 23, the imaging PK data in non-human primates and through modeling, we can predict that plasma exposure in humans will exceed the in vitro EC50 against hepatitis E replication in vitro across the internal administration at pharmacologically relevant dosing. On slide 24, this slide outlines a synopsis first-in-human study for AT587. The study will be conducted in a healthy volunteer with the primary objectives of evaluating safety, tolerability, and pharmacokinetics. It's a randomized, double-blind, placebo-controlled design, eventual dose escalation, and an embedded. We have incorporated standard sentinel dosing and gated escalation with dose progression informed by real-time safety and PK review. The study includes both single-ascending and multiple-ascending dose phases, providing flexibility to refine those levels as data emerged. I will now turn the call over to Andrea to discuss Atea Financials.

Thank you, Jean-Pierre. As Jornay mentioned in her introductory remarks, earlier today we issued a press release containing our financial results for the first quarter of 2026. The Statement of Operations and Balance Sheet are on Slides 26 and 27. We are pleased to report that our cash and investments were $256 million at March 31, 2026. The funds expended in the first quarter were principally directed to the advancement of our HCV program, evaluating the combination regimen of benifosfavir and rucosfavir, and to the advancement and completion of the CTA-enabling studies and manufacture of clinical trial trial material of AT587, our product candidate for the treatment of HEV. For R&D expenses, quarter over quarter, there was an increase in 2026 compared to 2025. The net increase in 2026 was principally driven by an increase in external spend related to our HCV Phase III clinical development and HEV preclinical development, offset by lower internal expenses, primarily related to a decrease in stock-based compensation, and lower payroll and payroll-related expenses. For G&A, quarter-over-quarter expenses decreased. The net decrease was primarily related to lower salaries and wages, lower stock-based compensation expense, and lower professional fees. In 2026, we intend to maintain our rigorous financial discipline while remaining laser focused on execution and value-creating advancement of our HCV and HEV product candidates. As we complete our Phase III trials, prepare to submit our regulatory filings, and engage in pre-launch activities, including the manufacturing of commercial launch supply, the substantial majority of our spending in 2026 will remain focused on the advancement of our hepatitis C program. With the resources in hand at the end of March, we expect to realize value-creating milestones for both our hepatitis C and our hepatitis E programs, and we project our cash runway to extend through 2027. I'll now hand the call back to Jean-Pierre for closing remarks.

Thank you, Andrea. In closing, 2026 is set to be a pivotal and value-creating year for a tear. We remain on track to deliver top-line phase-free results from CBR in mid-2026, followed by top-line phase-free results from C-Forward. We believe the target profile of our regimen, high efficacy, short treatment duration, a low risk of drug-drug interaction, and convenient dosing with no food effect position us to meaningfully address the needs of today's patients and prescribers. We believe our regimen fits seamlessly within the test-and-treat model of care, which has potential to expand the neuro-patient treated and accelerate progress toward the goal of HCV eradication in the United States and globally. Our HEV program is a strategic expansion of our antiviral pipeline aimed at addressing a major unmet need for highly vulnerable patient population with no approval treatment options today. We anticipate initiating our first in-human study mid-year, followed by the initiation of a proof-of-concept study around year end. With that, I will turn the call back over to the operator.

Thank you. At this time, we will be conducting a question-and-answer session. If you would like to ask a question, please press star 1 on your telephone keypad. Confirmation tone will indicate your line is in the question queue. If you'd like to remove your question from the queue, please press star 2. For participants using speaker equipment, it may be necessary to pick up your handset before pressing the star keys. Our first question is from Jonathan Miller with Evercore.

Hi, guys. Thanks so much for taking my question and looking forward to the upcoming data. Let's start with that. And I guess to what extent or what should we expect from the top line announcements for C-Beyond and then later in the year for C-Forward? What sorts of data should we expect in a top line press release versus what would be withheld for later publication at a medical meeting or a peer reviewed setting? So, A. And then second, when we think about commercial launch cadence and potential there, Assuming the phase threes bear out the differentiated product profile that you guys have been telling us about for a while, to what extent is commercial adoption going to be gated by contracting or by lumpy elements of getting your regimen in place in a program or a test-to-treat initiative that might have requirements on the drug it chooses?

Thank you, John. Okay, I will address the first question. The first question we will release as data with the CBR, the primary endpoints and the key secondary efficacy endpoint. So the SVR at week 24 after initiation of treatment in the modifying 10 to treat population, as well as the SVR at week 24 in the pair protocol population. John, you want to address the second part of the question?

Sure. So, John, thank you for the question. So currently our launch preparation are currently underway, and that includes the analysis and evaluation of the marketplace and understanding currently where the business segments are coming from, where likely future growth we're coming from, and also looking at where we will focus our activities. And that would be including across three segments from a commercial perspective of payers in terms of who we want to target and what their formulary status is right now and all those associated timelines, as well as, you know, preparations for Medicaid and Medicare areas. And the activities, we will pull, start executing them upon the data of our Phase 3 trials. And part of the question that you asked in terms of understanding what those timelines are and so forth, we will be evaluating all of that as we put into our penetration segments for the market.

Great. Thanks so much. Our next question is from Maxwell Score with Morgan Stanley.

Hello. This is Selena on for Max. Thanks for taking our question. With your market research based on Phase 2 results, what could you see in the Phase 3 that you would expect to impact prescriber or payer response?

My question?

Oh, sorry.

Like how…

Go ahead. Hello?

Oh, yes. So, with your market research being primarily focused on, like, the Phase 2 results, what could you see in the Phase 3 results that you think might impact the prescriber or payer response?

So I think we'll see things along the same, you know, trends that we saw in Phase 2, which is great efficacy with low potential for drug-drug interaction, no food effect, et cetera. So data consistent with Phase 2, which is what we see always in infectious diseases. The Phase 2 data translates very well into Phase 3. I don't know if John wants to add something to this.

No, I think I'm fine. And, you know, obviously we used the phase two data, and that data was very well received. And the only thing I'll tell you is that the payers and others are also very much interested in having a head-to-head trial because it's the first time. And it was something that's very intriguing and important to them as well. And it plays into the previous question about being ready for launch readiness. And, you know, one of those factors when you talk to the payers also is the head-to-head trial

was very helpful to them. Thank you. Our next question comes from Andy Shea with William Blair.

Thanks for taking our questions. First one, it has to do with the CBN. So looking at the Modified Intended Tree Population Analysis Plan, I think you basically calculated an SVR 12 of 95% based on the Phase II study, looking across the landscape, I believe Gilead published some of the non-compliant SCR-12 rates before, and it's in the low 90s, depending on the trials that you're looking at. So I'm curious about your thinking in terms of a superiority claim based on that delta. So just maybe commenting on the powering and sample size to see what level of confidence you have to achieve that milestone. Second question has to do with 587. You mentioned about the first in human study and the design. I guess two parts. One is for this first in human study, what is the treatment duration that you intend to test? And then, I guess, in the real world setting, what do you expect the treatment duration to be? Thank you. That is a great

question. First, look, our goal is to regiment patients and prescriber and with the attributes that we have and we continue to demonstrate through clinical trials and non-clinical studies as well, or clinical pharmacology studies as well. And so our goal is a non-inferiority trial, as you know, within a 5% margin. um when we talk about the real world uh including a true uh intent to treat uh you're right it's around uh 90 percent right closer if we take the same value in our phase two we were about the same as a true intent to treat as you know so look um let's see and you know we don't want to speculate it's going to be. We are going to evaluate, we think, we have sufficient power, definitely, for the non-inferiorities target. And we'll see the superiority probably because that we will increase even the power when we combine the trial. And there is actually an analysis that it is planned, and that has been shared with the FDA, combining those two study and evaluate it for potential superiority. For the AT587, the med is going to be a seven-day, a standard phase one, as we did with other indications. For the treatment duration, we foresee that we will start the proof-of-concept, which we believe we should be able to initiate by year-end, with 12 weeks of the chronic studies ongoing right now and we will have a peel out of three months sometimes in the fall so definitely on time to open a CTA on the on the proof of card cycling based on the phase one data that we will generate probably as you have seen now from what we predicted, 600 milligrams is a potential dose. QD or BID, we'll see. And that will be 12 weeks. Now, we will up front to continue this ecology status up to six months in rat and nine months in monkey, because potentially we'll see If we don't see a high SVRA with 12 weeks, we can potentially move to 24 weeks. Treatment duration is not an issue in this patient population. As you know, they take lifelong treatment against organ rejection. So compliance should be very good. And we have seen, so far, safety from a pre-medical standpoint have been good, and we can play in the phase one, as I have just indicated, related to a QD or BID regimen, whether 12 weeks or 24 weeks.

That's very helpful. Thank you.

Thank you. We have reached the end of the question and answer session. I would like to turn a call back now to Jean-Pierre Samodossi for closing remarks.

Thank you all for joining our first quarter 2026 earning conference call, and thank you for your continued support.

Thank you. This concludes today's conference. You may disconnect your lines at this time. Have a wonderful day.