NS5B polymerase x NS5A

Full Enrollment Achieved in Global Phase 2 Hepatitis C Virus (HCV) Study; Complete SVR12 Results Expected 4Q’24 Bemnifosbuvir and Ruzasvir HCV Data Presented at EASL: Support Best-in-Class Potential with High Antiviral Potency, Low Risk of Drug Interaction, Short Treatment Duration and High Barrier to Resistance Results from COVID-19 Global Phase 3 SUNRISE-3 Trial Expected 2H’24 Conference Call at 4:30 pm ET Today BOSTON, Aug. 07, 2024 (GLOBE NEWSWIRE) -- Atea Pharmaceuticals, Inc. (Nasdaq: AVIR) (Atea or Company), a clinical-stage biopharmaceutical company engaged in the discovery and development of oral antiviral therapeutics for serious viral diseases, today reported financial results for the second quarter ended June 30, 2024, and provided a business update. “The first half of 2024 was marked by strong operational execution and significant clinical progress. We completed patient enrollment in both the global Phase 3 SUNRISE-3 study of bemnifosbuvir for the treatment of COVID-19 and the global Phase 2 study evaluating the combination of bemnifosbuvir and ruzasvir in treatment-naïve, HCV-infected patients,” said Jean-Pierre Sommadossi, PhD, Chief Executive Officer and Founder of Atea. “Delivering treatment options to address the unmet needs for both COVID-19 and HCV patients remains of critical importance and we look forward to reporting results from both studies this year.” “Today, in the US, the reported annual incidence of approximately 100,000 new chronic HCV infections is outpacing the number of people cured with direct-acting antivirals. Many HCV patients take concomitant medications and in the wake of the opioid epidemic, people with substance abuse disorders and other populations with mental health disorders associated with poor medication adherence, are at the highest risk for HCV. New differentiated HCV therapies that offer low risk of drug-drug interactions combined with short treatment duration are required to address these needs,” continued Dr. Sommadossi. “The bemnifosbuvir and ruzasvir data we recently presented at the EASL Congress demonstrate a potential best-in-class profile and the promise of this combination to address the unmet needs of today’s HCV patient.” COVID-19 Phase 3 SUNRISE-3 Trial Update SUNRISE-3 Trial of Bemnifosbuvir in High-Risk Outpatients with COVID-19: The global, multicenter, randomized, double-blind, placebo-controlled, Phase 3 SUNRISE-3 trial is evaluating bemnifosbuvir or placebo administered concurrently with the locally available standard of care (SOC). SUNRISE-3 exclusively enrolled high-risk outpatients with mild or moderate COVID-19. Patients were randomized 1:1 to receive bemnifosbuvir 550 mg twice-daily (BID) or placebo BID for five days. Topline results from the study are expected in the second half of 2024. The primary endpoint of the SUNRISE-3 trial is all-cause hospitalization or death through Day 29 in the supportive care monotherapy cohort. In addition, secondary endpoints will measure patient outcomes in the trial through Day 60 post-treatment. The trial is comprised of two study populations based on the type of SOC administered at the investigator’s discretion: 1) the "supportive care population," evaluating bemnifosbuvir as monotherapy (primary analysis), and 2) the "combination antiviral population," assessing combination therapy if the SOC includes other compatible antiviral drugs against COVID-19 (secondary analysis). In this study, 2,221 patients were randomized into the supportive care monotherapy cohort and only 74 patients were randomized into the combination cohort, with 77% of all trial patients enrolled in the US. The clear preference by investigators to enroll patients in the monotherapy cohort highlights the continuing unmet medical need for new oral COVID-19 treatment options for high-risk patients. The SUNRISE-3 high risk patient population consists of those aged ≥70 years (regardless of other risk factors), individuals aged ≥55 years with one or more risk factors, those aged ≥50 years with two or more risk factors, and individuals aged ≥18 years with specific risk factors, including immunocompromised conditions, irrespective of COVID-19 vaccination status. COVID-19 Program for Second-Generation Protease Inhibitors: As part of a multi-pronged approach against COVID-19, Atea is engaged in efforts directed to the identification of second-generation protease inhibitors. Activities to select a novel proprietary compound with a differentiated profile are underway. Hepatitis C Virus (HCV) Phase 2 Update Phase 2 HCV Combination Study: In June 2024, Atea completed patient enrollment in the global Phase 2 clinical trial of bemnifosbuvir, an oral nucleotide NS5B polymerase inhibitor, in combination with ruzasvir, an oral NS5A inhibitor, in treatment-naïve, HCV-infected patients either without cirrhosis or with compensated cirrhosis. This study enrolled 275 patients, including the lead-in cohort of 60 patients without cirrhosis. The study is designed to evaluate the safety and efficacy of eight weeks of treatment with the combination consisting of once-daily bemnifosbuvir 550 mg and ruzasvir 180 mg. The primary endpoints of the study are safety and sustained virologic response (SVR) at Week 12 post-treatment (SVR12). Other virologic endpoints include virologic failure, SVR at Week 24 post-treatment (SVR24) and resistance. SVR12 results from all patients in the Phase 2 trial are expected during the fourth quarter of 2024. Positive Data for Bemnifosbuvir and Ruzasvir for Treatment of HCV Presented at European Association of the Study of Liver (EASL) Congress 2024: In June 2024, Atea presented at EASL new clinical data from the lead-in cohort (n=60) of the ongoing Phase 2 study of the combination of bemnifosbuvir and ruzasvir for the treatment of HCV. With an 8-week treatment duration, data from the lead-in cohort of non-cirrhotic patients showed a 97% SVR12 rate, which is the primary efficacy endpoint of the study. Among the 60 patients in the lead-in cohort, two subjects (GT1b and GT2b) experienced post-treatment relapse or failure. Each of these patients had low plasma drug levels and similar viral mutations at both the baseline and 12-weeks post-treatment timepoint, which indicate that the relapse or failure was due to treatment non-adherence rather than viral failure due to resistance. These results also showed a 100% SVR12 rate in participants infected with genotype 3 (n=13), a historically difficult-to-treat genotype of HCV. The combination regimen was well tolerated, with no drug-related serious adverse events or treatment discontinuations. In addition to the clinical trial results at EASL, Atea also presented preclinical data further demonstrating a high barrier to resistance and favorable pharmacokinetics for bemnifosbuvir and a low risk of drug-drug interactions for ruzasvir. Atea has previously reported a low risk of drug-drug interactions for bemnifosbuvir. Selected Fixed Dose Combination Tablet for Phase 3 Program: Atea recently selected the fixed dose combination (FDC) tablet for the Phase 3 program and subsequent commercialization. The selected FDC tablet achieved drug exposure comparable to individually administered bemnifosbuvir and ruzasvir used in Phase 2 and other studies. The selected FDC tablet will decrease the daily pill count from four tablets to two tablets, which is more convenient for patients. In addition, there was no food effect with the FDC tablet in a recent study that showed a high fat, high calorie meal did not affect the exposure of either bemnifosbuvir or ruzasvir. Second Quarter 2024 Financial Results Cash, Cash Equivalents and Marketable Securities: $502.2 million at June 30, 2024 compared to $578.1 million at December 31, 2023. Research and Development Expenses: Research and development expenses increased by $12.6 million from $22.1 million for the three months ended June 30, 2023 to $34.7 million for the three months ended June 30, 2024. The increase was primarily driven by higher external spend related to the advancement of both our Phase 3 COVID-19 SUNRISE-3 clinical trial and our Phase 2 clinical trial of the combination of bemnifosbuvir and ruzasvir for the treatment of HCV. This increase was partially offset by a reduction of approximately $1.0 million in internal costs primarily due to a decrease in consulting and other research and development expenses. General and Administrative Expenses: General and administrative expenses decreased by $1.0 million from $13.2 million for the three months ended June 30, 2023 to $12.2 million for the three months ended June 30, 2024. The net decrease was primarily related to lower professional fees. Interest Income and Other, Net: Interest income and other, net, decreased by $0.7 million for the three months ended June 30, 2024 compared to the three months ended June 30, 2023, primarily due to lower investment balances. Income Taxes: Income tax expense of $0.2 million remained unchanged for each of the three months ended June 30, 2024 and June 30, 2023. Condensed Consolidated Statement of Operations and Comprehensive Loss(in thousands, except share and per share amounts)(unaudited) Three Months EndedJune 30, Six Months EndedJune 30, 2024 2023 2024 2023 Operating expenses Research and development$34,696 $22,063 $92,271 $51,017 General and administrative 12,220 13,172 24,451 25,787 Total operating expenses 46,916 35,235 116,722 76,804 Loss from operations (46,916) (35,235) (116,722) (76,804)Interest income and other, net 6,637 7,303 13,505 13,602 Loss before income taxes (40,279) (27,932) (103,217) (63,202)Income tax expense (243) (251) (474) (448)Net loss$(40,522) $(28,183) $(103,691) $(63,650)Other comprehensive loss Unrealized gain (loss) on available-for-sale investments (99) (3) (487) 374 Comprehensive loss$(40,621) $(28,186) $(104,178) $(63,276)Net loss per share - basic and diluted$(0.48) $(0.34) $(1.23) $(0.76)Weighted-average number of common shares - basic and diluted 84,253,700 83,399,377 84,069,646 83,361,398 Selected Condensed Consolidated Balance Sheet Data(in thousands)(unaudited) June 30, 2024 December 31, 2023 Cash, cash equivalents and marketable securities$502,214 $578,106 Working capital(1) 479,750 558,079 Total assets 510,384 594,968 Total liabilities 33,914 39,776 Total stockholder's equity 476,470 555,192 (1) Atea defines working capital as current assets less current liabilities. See the Company’s condensed consolidated financial statements in its Quarterly Report on Form 10-Q for the three months ended June 30, 2024 for further detail regarding its current assets and liabilities. Conference Call and Webcast Atea will host a conference call and live audio webcast to discuss second quarter 2024 financial results and provide a business update today at 4:30 p.m. ET. To access the live conference call, participants may register here. The live audio webcast of the call will be available under "Events and Presentations" in the Investor Relations section of the Atea Pharmaceuticals website at ir.ateapharma.com. To participate via telephone, please register in advance here. Upon registration, all telephone participants will receive a confirmation email detailing how to join the conference call, including the dial-in number along with a unique passcode and registrant ID that can be used to access the call. While not required, it is recommended that participants join the call ten minutes prior to the scheduled start. An archive of the audio webcast will be available on Atea Pharmaceuticals’ website approximately two hours after the conference call and will remain available for at least 90 days following the event. About Bemnifosbuvir for COVID-19 Bemnifosbuvir, an oral nucleotide polymerase inhibitor, targets the SARS-CoV-2 RNA polymerase (nsp12), a highly conserved gene which is responsible for both replication and transcription of SARS-CoV-2. Bemnifosbuvir has a unique mechanism of action, with dual targets consisting of chain termination (RdRp) and nucleotityltransferase (NiRAN) inhibition, which have the potential to create a high barrier to resistance. In vitro data confirmed that bemnifosbuvir is active with similar efficacy against all variants of concern and variants of interest that have been tested, including the recent subvariants BA.5, XBB, EG.5.1 and JN.1. The evaluation of bemnifosbuvir for the treatment of COVID-19 has been granted Fast Track designation by the US Food and Drug Administration (FDA). About Bemnifosbuvir and Ruzasvir for Hepatitis C Virus (HCV) Bemnifosbuvir, an oral HCV NS5B inhibitor, has been shown in in vitro studies to be approximately 10-fold more active than sofosbuvir (SOF) against a panel of laboratory strains and clinical isolates of HCV GT 1–5. In vitro studies have also demonstrated bemnifosbuvir remained fully active against SOF resistance-associated strains (S282T), with up to 58-fold more potency than SOF. The pharmacokinetic (PK) profile of bemnifosbuvir supports once-daily dosing for the treatment of HCV. Across both HCV and COVID-19 programs, bemnifosbuvir has been administered to over 2,200 subjects and has been well-tolerated at doses up to 550 mg for durations up to 12 weeks in healthy subjects and patients. Ruzasvir, an oral HCV NS5A inhibitor, has demonstrated highly potent and pan-genotypic antiviral activity in preclinical (picomolar range) and clinical studies. Ruzasvir has been administered to over 1,500 HCV-infected patients at daily doses of up to 180 mg for 12 weeks and has demonstrated a favorable safety profile. Ruzasvir’s PK profile supports once-daily dosing. About Atea Pharmaceuticals Atea is a clinical stage biopharmaceutical company focused on discovering, developing and commercializing oral antiviral therapies to address the unmet medical needs of patients with serious viral infections. Leveraging the Company’s deep understanding of antiviral drug development, nucleos(t)ide chemistry, biology, biochemistry and virology, Atea has built a proprietary nucleos(t)ide prodrug platform to develop novel product candidates to treat single stranded ribonucleic acid, or ssRNA, viruses, which are a prevalent cause of serious viral diseases. Atea plans to continue to build its pipeline of antiviral product candidates by augmenting its nucleos(t)ide platform with other classes of antivirals that may be used in combination with its nucleos(t)ide product candidates. Currently, Atea is focused on the development of orally-available antiviral agents for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes COVID-19, and hepatitis C virus (HCV). For more information, please visit www.ateapharma.com. Forward-Looking Statements This press release includes “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995. Forward-looking statements in this press release include but are not limited to the date and time of the Company’s conference call and audio webcast and the anticipated time of release of clinical trial results from the Company’s COVID-19 and HCV programs. When used herein, words including “expects,” “may,” “will,” “anticipates,” “plans”, and similar expressions are intended to identify forward-looking statements. In addition, any statements or information that refer to expectations, beliefs, plans, projections, objectives, performance or other characterizations of future events or circumstances, including any underlying assumptions, are forward-looking. All forward-looking statements are based upon the Company’s current expectations and various assumptions. The Company believes there is a reasonable basis for its expectations and beliefs, but they are inherently uncertain. The Company may not realize its expectations, and its beliefs may not prove correct. Actual results could differ materially from those described or implied by such forward-looking statements as a result of various important factors, including, without limitation, the important factors discussed and updated from time to time under the caption “Risk Factors” in the reports the Company files with the SEC, including annual reports on Form 10-K, quarterly reports on Form 10-Q, current reports on Form 8-K and other filings each of which are accessible on the SEC’s website at www.sec.gov. These and other important factors could cause actual results to differ materially from those indicated by the forward-looking statements made in this press release. Any such forward-looking statements represent management’s estimates as of the date of this press release. While the Company may elect to update such forward-looking statements at some point in the future, except as required by law, it disclaims any obligation to do so, even if subsequent events cause our views to change. These forward-looking statements should not be relied upon as representing the Company’s views as of any date subsequent to the date of this press release. Contacts Jonae BarnesSVP, Investor Relations and Corporate Communications617-818-2985barnes.jonae@ateapharma.com Will O’ConnorPrecision AQ212-362-1200will.oconnor@precisionaq.com

97% SVR12 Rate Observed with 8 Weeks of Treatment in Lead-In Cohort of HCV-Infected Patients in Ongoing Phase 2 Clinical Study EASL Presentations Continue to Support Best-in-Class Potential with High Antiviral Potency, Short Treatment Duration, Low Risk of Drug Interaction and High Barrier to Resistance BOSTON, June 05, 2024 (GLOBE NEWSWIRE) -- Atea Pharmaceuticals, Inc. (Nasdaq: AVIR) (“Atea”), a clinical-stage biopharmaceutical company engaged in the discovery and development of oral antiviral therapeutics for serious viral diseases, today announced new data from the lead-in cohort (n=60) of the Company’s ongoing Phase 2 combination study of bemnifosbuvir, an oral nucleotide NS5B polymerase inhibitor, and ruzasvir, an oral NS5A inhibitor, for the treatment of hepatitis C virus (HCV). With an 8-week treatment duration, the Phase 2 data from the lead-in cohort of non-cirrhotic patients showed a 97% sustained virologic response rate at 12 weeks post-treatment (SVR12), which is the primary efficacy endpoint of the study. The Company will also present preclinical data further demonstrating a high barrier to resistance and pharmacokinetics for bemnifosbuvir and a low risk of drug-drug interactions for ruzasvir. These data are being presented at the European Association for the Study of the Liver (EASL) Congress taking place June 5-8, 2024, in Milan, Italy. “Today, new challenges are hindering progress towards our goal of HCV elimination in the U.S. and globally. Patient demographics have changed, and the pace of new HCV infections is quickly outpacing the rate of those being treated. It is apparent that further innovations are required to address the needs of today’s HCV-infected patients,” said Jean-Pierre Sommadossi, PhD, Chief Executive Officer and Founder of Atea Pharmaceuticals. “The data being presented at EASL demonstrate a potential best-in-class pro combines the most compelling attributes of current HCV drug treatments through the innovative combination of bemnifosbuvir and ruzasvir. We look forward to reporting the full results from our ongoing Phase 2 study during the second half of this year.” Results from the lead-in cohort of the Phase 2 study also showed a 100% SVR12 rate in participants infected with genotype 3 (n=13), a historically difficult-to-treat genotype of HCV. The combination regimen was well tolerated, with no drug-related severe adverse events (SAEs) or treatment discontinuations. Based on these positive data from the lead-in cohort, the Phase 2 study continues, with the aim of enrolling up to an additional 220 subjects, including those with compensated cirrhosis. “Today, many of my HCV patients present with other conditions requiring multiple concurrent therapies and complicated lives,” said Eric Lawitz, MD, The Texas Liver Institute, Clinical Professor of Medicine, University of Texas Health San Antonio. “I am excited about the initial bemnifosbuvir and ruzasvir combination data. The combination of a short 8-week treatment duration, a low risk of drug-drug interactions, and robust antiviral efficacy across all genotypes makes this an attractive regimen.” More than 2 million people in the U.S. are living with chronic HCV, and approximately 100,000 new chronic cases are diagnosed each year. HCV diagnoses continually outpace annual treatment rates, as less than a third of those diagnosed with HCV receive timely treatment. Data Presented at EASL Include: Poster Title: Lead-in Cohort Results From a Phase 2 Study of a Novel 8-Week Combination Regimen of Bemnifosbuvir and Ruzasvir in Patients with Chronic Hepatitis C Virus Infection (THU-382) Conclusion: Data from the lead-in cohort of 60 patients in the Phase 2 clinical trial of bemnifosbuvir and ruzasvir in HCV-infected subjects showed a high SVR12 rate of 97% in the lead-in cohort with a short 8-week duration of treatment. The primary endpoints of the study are safety and SVR12. Viral kinetics were similar in genotype 1 and genotype 3 infected subjects, including a 100% SVR12 rate in historically difficult-to-treat genotype 3 infected subjects. The combination was generally safe and well tolerated. There were no drug-related serious adverse events or treatment discontinuations, and adverse events were mostly mild. Poster Title: Bemnifosbuvir is a Potent HCV NS5B Inhibitor with a Favorable Antiviral Pro High Resistance Barrier (SAT-402) Conclusion: Viral resistance is an important consideration for direct-acting antiviral (DAA) use as it may impact the efficacy of treatments for HCV infection. Results demonstrated that bemnifosbuvir is at least ten-fold more potent than sofosbuvir, a medication to treat HCV infections, across all genotypes tested and is not resistant to resistance-associated substitutions (RASs) that have been found to alter the activity of sofosbuvir. While the C223H mutation was found to be the primary bemnifosbuvir RAS in genotype 1b, multiple additional substitutions at other NS5B regions were required to confer meaningful resistance, suggesting that bemnifosbuvir provides a high barrier to resistance. Based upon the data demonstrated to date, it is expected that the bemnifosbuvir and ruzasvir combination should have a more compelling antiviral pro major HCV NS5A RAVs than the current standard of care. Poster Title: Absorption, Distribution, Metabolism, and Excretion of [14C]-Bemnifosbuvir in Rats (SAT-411) Conclusion: This preclinical study in rats was conducted to better understand the tissue distribution, metabolites, and excretion routes following bemnifosbuvir treatment. Following a single oral dose in rats, bemnifosbuvir has favorable overall absorption, distribution, metabolism, and excretion (ADME) properties, including good bioavailability (>60%) and wide distribution to tissues with low penetration into the brain. Bemnifosbuvir was highly and rapidly metabolized to the metabolite AT-273, consistent with the proposed metabolic and activation pathway. Poster Title: Low Risk of Drug-Drug Interactions for Ruzasvir Based Upon In Vitro Metabolism and Transporter Interaction Studies (SAT-412) Conclusion: Many patients infected with HCV are also taking multiple co-medications, which may impact treatment decisions. This preclinical study aimed to further understand the risk of drug-drug interactions (DDIs) for ruzasvir by analyzing its metabolism in human liver microsomes and cells. Based on these in vitro data and static DDI risk assessment models, ruzasvir has a low potential to be a perpetrator of DDIs via inhibition or induction of CYP450. Similarly, it has a low potential to inhibit OATP1B1 and OATP1B3 transporters. The relevance of bile salt export pump (BSEP) inhibition to DDIs is limited. About Hepatitis C Virus Hepatitis C virus (HCV) is a blood-borne, positive-sense, single-stranded (ss)RNA virus that primarily infects liver cells. HCV is a leading cause of chronic liver disease and liver transplants, spreading via blood transfusion, hemodialysis, and needle sticks. An estimated 50 million people globally live with chronic HCV infection, with approximately 1 million new infections and 242,000 deaths occurring each year. Most HCV-related deaths are due to liver scarring (cirrhosis) and liver cancer (hepatocellular carcinoma). Injection drug use accounts for around 30% of new HCV cases globally and approximately 60% in the U.S. Annually, HCV diagnoses in the U.S. outpace treatment rates, as less than a third of those diagnosed with HCV receive timely treatment. About Bemnifosbuvir and Ruzasvir for Hepatitis C Virus (HCV) Bemnifosbuvir is an oral, purine nucleotide prodrug designed to inhibit viral replication by impairing viral RNA polymerase, a key component in the replication machinery of enveloped positive single-stranded RNA viruses, such as human coronaviruses and HCV. Atea is developing bemnifosbuvir in combination with ruzasvir, an oral NS5A inhibitor for the treatment of HCV. As single agents, both bemnifosbuvir and ruzasvir have demonstrated potent pan-genotypic antiviral activity against HCV. The combination of bemnifosbuvir and ruzasvir has exhibited synergistic in vitro activity against HCV with no pharmacokinetic (PK) drug-drug interactions in healthy volunteers. In vitro studies have shown bemnifosbuvir to be approximately 10-fold more active than sofosbuvir (SOF) against a panel of laboratory strains and clinical isolates of HCV GT 1–5. In vitro studies have also demonstrated that bemnifosbuvir remained fully active against SOF resistance-associated strains (S282T), with up to 58-fold more potency than SOF. The PK pro bemnifosbuvir supports once-daily dosing for the treatment of HCV. Across both HCV and COVID-19 programs, bemnifosbuvir has been administered to over 2,100 subjects and has been well-tolerated at doses up to 550 mg for durations up 12 weeks in healthy subjects and patients. Ruzasvir has demonstrated highly potent and pan-genotypic antiviral activity in preclinical (picomolar range) and clinical studies. Ruzasvir has been administered to over 1,200 HCV-infected patients at daily doses of up to 180 mg for 12 weeks and has demonstrated a favorable safety profile. Ruzasvir’s PK pro once-daily dosing. About the Phase 2 Study Atea is currently conducting a global Phase 2 clinical trial in treatment-naïve, chronic HCV-infected patients either without cirrhosis or with compensated cirrhosis. This study is designed to evaluate the safety and efficacy of eight weeks of treatment with the combination consisting of once-daily bemnifosbuvir 550 mg and ruzasvir 180 mg. Up to approximately 280 treatment-naïve patients across all HCV genotypes, including the lead-in cohort of 60 patients without cirrhosis, are expected to be enrolled in this Phase 2 clinical trial. The primary endpoints of the study are safety and sustained virologic response (SVR) at 12 weeks post-treatment (SVR12). Other virologic endpoints include virologic failure, SVR at 24 weeks post-treatment (SVR24) and resistance. Topline results from all patients enrolled in the Phase 2 study are anticipated in the second half of 2024. About Atea Pharmaceuticals Atea is a clinical-stage biopharmaceutical company focused on discovering, developing and commercializing oral antiviral therapies to address the unmet medical needs of patients with serious viral infections. Leveraging the Company’s deep understanding of antiviral drug development, nucleos(t)ide chemistry, biology, biochemistry and virology, Atea has built a proprietary nucleos(t)ide prodrug platform to develop novel product candidates to treat single stranded ribonucleic acid, or ssRNA, viruses, which are a prevalent cause of serious viral diseases. Atea plans to continue to build its pipeline of antiviral product candidates by augmenting its nucleos(t)ide platform with other classes of antivirals that may be used in combination with its nucleos(t)ide product candidates. Currently, Atea is focused on the development of orally-available antiviral agents for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes COVID-19, and hepatitis C virus (HCV). For more information, please visit . Forward-Looking Statements This press release includes “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995. Forward-looking statements in this press release include but are not limited to the Company’s plans relating to the date and time of the presentations at the conference, the time of anticipated release of additional clinical data and the potential of bemnifosbuvir in combination with ruzasvir to treat HCV. When used herein, words including “expects,” “may,” “will,” “anticipates,” “plans,” and similar expressions are intended to identify forward-looking statements. In addition, any statements or information that refer to expectations, beliefs, plans, projections, objectives, performance or other characterizations of future events or circumstances, including any underlying assumptions, are forward-looking. All forward-looking statements are based upon the Company’s current expectations and various assumptions. The Company believes there is a reasonable basis for its expectations and beliefs, but they are inherently uncertain. The Company may not realize its expectations, and its beliefs may not prove correct. Actual results could differ materially from those described or implied by such forward-looking statements as a result of various important factors, including, without limitation, the important factors discussed and updated from time to time under the caption “Risk Factors” in the reports the Company files with the SEC, including annual reports on Form10-K, quarterly reports on Form10-Q, current reports on Form 8-K and other filings each of which are accessible on the SEC’s website at These and other important factors could cause actual results to differ materially from those indicated by the forward-looking statements made in this press release. Any such forward-looking statements represent management’s estimates as of the date of this press release. While the Company may elect to update such forward-looking statements at some point in the future, except as required by law, it disclaims any obligation to do so, even if subsequent events cause our views to change. These forward-looking statements should not be relied upon as representing the Company’s views as of any date subsequent to the date of this press release. Contacts Jonae Barnes SVP, Investor Relations and Corporate Communications 617-818-2985 Barnes.jonae@ateapharma.com Will O’Connor Precision AQ 212-362-1200 will.oconnor@precisionaq.com

Presentations to Include New Antiviral Efficacy Results, Including SVR12 Data, from Lead-In Cohort of Ongoing Phase 2 HCV Trial Data Also Highlight the High Prevalence of Pre-Existing NS5A Resistance-Associated Substitutions (RAS) Detected in HCV-infected Patients BOSTON, May 22, 2024 (GLOBE NEWSWIRE) -- Atea Pharmaceuticals, Inc. (Nasdaq: AVIR) (“Atea”), a clinical-stage biopharmaceutical company engaged in the discovery and development of oral antiviral therapeutics for serious viral diseases, today announced the Company will present new efficacy results, including SVR12 data (primary endpoint), from the Phase 2 lead-in cohort evaluating the combination of bemnifosbuvir (an oral nucleotide NS5B polymerase inhibitor) and ruzasvir (an oral NS5A inhibitor) for the treatment of hepatitis C virus (HCV) at the European Association for the Study of the Liver (EASL) Congress 2024, taking place June 5-8, 2024 in Milan, Italy. Preclinical data further demonstrating bemnifosbuvir’s high barrier to resistance and pharmacokinetics and ruzasvir’s low risk of drug-drug interactions will also be presented. “Despite current HCV treatments, progress toward eliminating the virus in the U.S. has slowed, and new chronic cases exceed cure rates. In the decade since the first direct acting antiviral treatments were introduced, both the virus and the patient population have changed significantly, including the emergence of resistant mutations,” said Jean-Pierre Sommadossi, PhD, Chief Executive Officer and Founder of Atea Pharmaceuticals. “We need new HCV treatments that address the needs of today’s patients and feature a best-in-class treatment profile with high antiviral potency, short treatment duration, potential for low risk of drug-drug interactions and a high barrier to resistance. We look forward to sharing our data at EASL Congress 2024, which will reinforce the potential of this combination to treat HCV as it exists today.” More than 2 million people in the U.S. are living with chronic HCV, and approximately 100,000 new chronic cases are diagnosed each year. HCV diagnoses continually outpace annual cure rates, as less than a third of those diagnosed with HCV receive timely treatment. As HCV persists, six main variants, or genotypes, have emerged. Genotype 1 is the most prevalent, while some variants, such as genotype 3, can be more difficult to treat due to mutations that enable the virus to develop resistance against existing HCV drugs. The full datasets for the accepted abstracts will become available on the EASL Congress website following the embargo lift on Wednesday, June 5th at 8:00 AM Central European Time (CEST). Details for the EASL Congress presentations are as follows: Poster ID: THU-382Title: Lead-in Cohort Results From a Phase 2 Study of a Novel 8-Week Combination Regimen of Bemnifosbuvir and Ruzasvir in Patients with Chronic Hepatitis C Virus InfectionPresenting Author: Alina Jucov, M.D., Ph.D.Date and Time: June 6, 2024, 8:30 AM CEST Poster ID: SAT-402Title: Bemnifosbuvir is a Potent HCV NS5B Inhibitor with a Favorable Antiviral Profile and High Resistance BarrierPresenting Author: Qi Huang, Ph.D.Date and Time: June 8, 2024, 8:30 AM CEST Poster ID: SAT-411Title: Absorption, Distribution, Metabolism, and Excretion of [14C]-Bemnifosbuvir in RatsPresenting Author: Alex Vo, Ph.D.Date and Time: June 8, 2024, 8:30 AM CEST Poster ID: SAT-412Title: Low Risk of Drug-Drug Interactions for Ruzasvir Based Upon In Vitro Metabolism and Transporter Interaction StudiesPresenting Author: Alex Vo, Ph.D.Date and Time: June 8, 2024, 8:30 AM CEST About Bemnifosbuvir and Ruzasvir for Hepatitis C Virus (HCV) Bemnifosbuvir is an oral, purine nucleotide prodrug designed to inhibit viral replication by impairing viral RNA polymerase, a key component in the replication machinery of enveloped positive single-stranded RNA viruses, such as human coronaviruses and HCV. Atea is developing bemnifosbuvir in combination with ruzasvir, an oral NS5A inhibitor for the treatment of HCV. As single agents, both bemnifosbuvir and ruzasvir have demonstrated potent pan-genotypic antiviral activity against HCV. The combination of bemnifosbuvir and ruzasvir has exhibited synergistic in vitro activity against HCV with no pharmacokinetic (PK) drug-drug interactions in healthy volunteers. In vitro studies have shown bemnifosbuvir to be approximately 10-fold more active than sofosbuvir (SOF) against a panel of laboratory strains and clinical isolates of HCV GT 1–5. In vitro studies have also demonstrated that bemnifosbuvir remained fully active against SOF resistance-associated strains (S282T), with up to 58-fold more potency than SOF. The PK profile of bemnifosbuvir supports once-daily dosing for the treatment of HCV. Across both HCV and COVID-19 programs, bemnifosbuvir has been administered to over 2,100 subjects and has been well-tolerated at doses up to 550 mg for durations up 12 weeks in healthy subjects and patients. Ruzasvir has demonstrated highly potent and pan-genotypic antiviral activity in preclinical (picomolar range) and clinical studies. Ruzasvir has been administered to over 1,200 HCV-infected patients at daily doses of up to 180 mg for up to 12 weeks and has demonstrated a favorable safety profile. Ruzasvir’s PK profile supports once-daily dosing. About the Phase 2 Study Atea is currently conducting a global Phase 2 clinical trial of bemnifosbuvir in treatment-naïve, chronic HCV-infected patients either without cirrhosis or with compensated cirrhosis. This study is designed to evaluate the safety and efficacy of eight weeks of treatment with the combination consisting of once-daily bemnifosbuvir 550 mg and ruzasvir 180 mg. Up to approximately 280 chronically infected, treatment-naïve patients across all HCV genotypes, including the lead-in cohort of 60 patients without cirrhosis, are expected to be enrolled in this Phase 2 clinical trial. The primary endpoints of the study are safety and sustained virologic response (SVR) at Week 12 post-treatment (SVR12). Other virologic endpoints include virologic failure, SVR at Week 24 post-treatment (SVR24) and resistance. Results from the 60-patient lead-in cohort announced in February 2024 demonstrated a 98% SVR4 rate across genotypes from 58 of 59 patients, which include a patient with poor adherence who did not achieve SVR4 and exclude one patient who did not attend the Week 4 post-treatment follow-up. Topline results from all patients enrolled in the Phase 2 study are anticipated in the second half of 2024. About Atea Pharmaceuticals Atea is a clinical-stage biopharmaceutical company focused on discovering, developing and commercializing oral antiviral therapies to address the unmet medical needs of patients with serious viral infections. Leveraging the Company’s deep understanding of antiviral drug development, nucleos(t)ide chemistry, biology, biochemistry and virology, Atea has built a proprietary nucleos(t)ide prodrug platform to develop novel product candidates to treat single stranded ribonucleic acid, or ssRNA, viruses, which are a prevalent cause of serious viral diseases. Atea plans to continue to build its pipeline of antiviral product candidates by augmenting its nucleos(t)ide platform with other classes of antivirals that may be used in combination with its nucleos(t)ide product candidates. Currently, Atea is focused on the development of orally-available antiviral agents for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes COVID-19, and hepatitis C virus (HCV). For more information, please visit www.ateapharma.com. Forward-Looking Statements This press release includes “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995. Forward-looking statements in this press release include but are not limited to the Company’s plans relating to the date and time of the presentations at the conference and the potential of bemnifosbuvir in combination with ruzasvir to treat HCV if successfully developed. trial results. When used herein, words including “expects,” “may,” “will,” “anticipates,” “plans,” and similar expressions are intended to identify forward-looking statements. In addition, any statements or information that refer to expectations, beliefs, plans, projections, objectives, performance or other characterizations of future events or circumstances, including any underlying assumptions, are forward-looking. All forward-looking statements are based upon the Company’s current expectations and various assumptions. The Company believes there is a reasonable basis for its expectations and beliefs, but they are inherently uncertain. The Company may not realize its expectations, and its beliefs may not prove correct. Actual results could differ materially from those described or implied by such forward-looking statements as a result of various important factors, including, without limitation, the important factors discussed and updated from time to time under the caption “Risk Factors” in the reports the Company files with the SEC, including annual reports on Form 10-K, quarterly reports on Form 10-Q, current reports on Form 8-K and other filings each of which are accessible on the SEC’s website at www.sec.gov. These and other important factors could cause actual results to differ materially from those indicated by the forward-looking statements made in this press release. Any such forward-looking statements represent management’s estimates as of the date of this press release. While the Company may elect to update such forward-looking statements at some point in the future, except as required by law, it disclaims any obligation to do so, even if subsequent events cause our views to change. These forward-looking statements should not be relied upon as representing the Company’s views as of any date subsequent to the date of this press release. Contacts Jonae BarnesSVP, Investor Relations and Corporate Communications617-818-2985Barnes.jonae@ateapharma.com Will O’ConnorStern Investor Relations 212-362-1200will.oconnor@sternir.com