March 28, 2022

Atea Pharmaceuticals Reports Nonclinical Bemnifosbuvir (AT-527) Toxicology Data at Society of Toxicology 61st Annual Meeting

Bemnifosbuvir Demonstrated Favorable Overall Nonclinical Safety Profile, Including Lack of Reproductive and Development Toxicity in Animal Models

BOSTON, March 28, 2022 (GLOBE NEWSWIRE) -- Atea Pharmaceuticals, Inc. (Nasdaq: AVIR) (“Atea”), a clinical-stage biopharmaceutical company, today presented two posters highlighting nonclinical data demonstrating the nonclinical safety of bemnifosbuvir (AT-527) at the Society of Toxicology (SOT) 61st Annual Meeting taking place in San Diego, California from March 27 – 31, 2022. Atea’s poster board presentation P857 was selected by the SOT Risk Assessment Specialty Selection Executive Committee as a top ten abstract this year.

“We are very pleased with the favorable nonclinical toxicity profile for bemnifosbuvir as evidenced by the results of the studies presented today,” said Jean-Pierre Sommadossi, Ph.D., Chief Executive Officer and Founder of Atea Pharmaceuticals. “We believe the favorable toxicity profile of bemnifosbuvir makes it ideal for clinical development in broad patient populations and in oral combination regimens for the treatment of severe viral infections, such as COVID-19 and hepatitis C.”

The following poster boards highlighting the favorable bemnifosbuvir nonclinical safety assessment and toxicology data were presented:

Abstract 4793/Poster Board P857: Lack of Reproductive and Developmental Toxicity for AT-527, an Oral Purine Nucleotide Prodrug for COVID-19 Infection presented by Shouqi Luo, Ph.D., Executive Director of Toxicology at Atea and authored by Dr. Luo and other Atea scientists.

  • Highlights of the data showed that:
    • There were no AT-527-related effects on the fertility, reproduction, embryofetal and postnatal development in rats.
    • In rabbits, there were no AT-527-related embryofetal abnormalities at doses up to 100 mg/kg/day even in the presence of evident maternal toxicities at 100 mg/kg/day, i.e., body weight loss, abortions, and mortalities, which were secondary to reduced food consumption.
    • The maternal toxicity of AT-527 in rabbits was confounded by the vehicle which itself resulted in reduced food consumption and body weight loss noted in a 7-day tolerability study in nonpregnant female rabbits.

Abstract 4794/Poster Board P858: Characterization of the Toxicity Profile of AT-527, a Novel Guanosine Nucleotide Prodrug with Antiviral Activity for COVID-19 Infection presented by Steven Good, Executive Vice President, Preclinical Science at Atea, and authored by other Atea scientists.

  • Highlights of the data showed that:
    • AT-527 exhibited low potential for QTc prolongation in rats and monkeys.
    • AT-527 and its metabolites were negative in a battery of in vitro and in vivo genetic toxicity assays.
    • In repeat dose oral toxicity studies in rats and monkeys up to 13 weeks, no target organ toxicity was identified.
    • Dose-related reversible liver weight increases were noted in rats with correlating hepatocellular hypertrophy in the rat 13-week study. These changes were considered adaptive.

About Atea Pharmaceuticals

Atea Pharmaceuticals is a clinical stage biopharmaceutical company focused on discovering, developing and commercializing oral therapies to address the unmet medical needs of patients with life-threatening viral diseases. Leveraging the Company’s deep understanding of antiviral drug development, nucleos(t)ide chemistry, biology, biochemistry and virology, Atea has built a proprietary nucleotide prodrug platform to develop novel product candidates to treat single stranded ribonucleic acid, or ssRNA, viruses, which are a prevalent cause of severe 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 difficult-to-treat, life-threatening viral infections, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes COVID-19, hepatitis C virus (HCV), dengue virus and respiratory syncytial virus (RSV). For more information, please visit

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. All statements contained in this press release that do not relate to matters of historical fact should be considered forward-looking statements, including without limitation statements regarding our expectations surrounding the potential of our product candidates, including bemnifosbuvir combination product candidates, and expectations regarding our pipeline, including trial design and development timelines. These statements are neither promises nor guarantees, but involve known and unknown risks, uncertainties and other important factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements, including, but not limited to, the uncertainty around and costs associated with the clinical development of bemnifosbuvir as a potential treatment for COVID-19 and HCV. These and other important factors discussed under the caption “Risk Factors” in our Annual Report on Form 10-K for the year ended December 31, 2021 and our other filings with the SEC 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 we may elect to update such forward-looking statements at some point in the future, we disclaim any obligation to do so, even if subsequent events cause our views to change.


Jonae Barnes
SVP, Investor Relations and Corporate Communications

Will O’Connor
Stern Investor Relations