Ascletis Announces U.S. FDA Approval of Conducting a Phase IIa Clinical Trial for ASC10 to Treat Respiratory Syncytial Virus Infection

    --Respiratory syncytial virus (RSV) infection treatment remains huge unmet medical needs and there is no effective drug for treatment globally so far

    --Dosage of 800 mg ASC10, twice daily was selected to conduct a Phase IIa study in patients with RSV infection

    --Preclinical research showed that ASC10-A is a potent inhibitor against RSV both in vitro and in vivo

    HANGZHOU and SHAOXING, China, Jan. 31, 2023 /PRNewswire/ -- Ascletis Pharma Inc. (HKEX: 1672, "Ascletis") announces today that the U.S. Food and Drug Administration ("FDA") has approved to conduct a Phase IIa clinical trial for ASC10 to treat respiratory syncytial virus (RSV) infection. Based on available data, dosage of 800 mg ASC10, twice daily was selected to conduct a randomized, double-blind, placebo-controlled Phase IIa study to evaluate the antiviral activity, safety, tolerability and pharmacokinetics of ASC10 tablets in patients with mild or moderate RSV infection.

    ASC10 is an oral double prodrug. After oral administration, ASC10 is rapidly and completely converted in vivo into the active metabolite ASC10-A, also known as β -D-N4-hydroxycytidine (NHC) or EIDD-1931. Preclinical research[1] showed that ASC10-A (NHC) is a potent inhibitor with EC50 of 0.51 to 0.6 uM against two RSV clinical isolates using in vitro infection assay in HEp-2 cells. Furthermore, preclinical research[1] also demonstrated that ASC10-A (NHC) is efficacious in a mouse RSV infection model.

    Ascletis has been granted a patent of ASC10 and its derivatives, and their uses to treat multiple virus infections by the United States Patent and Trademark Office (USPTO), including SARS-CoV-2, monkeypox virus and RSV.

    RSV is the most common cause of bronchiolitis (inflammation of the small airways in the lung) and pneumonia (infection of the lungs) in children younger than 1 year of age in the United States[2] and causes approximately 58,000 hospitalizations among children under five annually[3]. RSV infection is estimated to cause about 14,000 annual deaths in U.S. adults over age 65. Globally, RSV affects an estimated 64 million people and causes 160,000 deaths each year [3].

    RSV infection treatment remains huge unmet medical needs and there is no effective drug for treatment so far. According to the report from Astute Analytica, the global market of RSV therapies is expected to grow at CAGR of 14.9% from 2022-2027 and reach revenue of US$4.2 billion by 2027[4].

     "RSV poses a persistent threat to infants and the elderly population, and so far there is no effective drug available worldwide. We are glad that ASC10 has obtained the U.S. FDA approval to conduct a Phase IIa study to treat RSV infection in patients, which is a new milestone of Ascletis' R&D in treatment for viral diseases. Preclinical research showed that ASC10-A is a potent inhibitor against RSV both in vitro and in vivo, and we will accelerate the Phase IIa clinical study to benefit patients worldwide." said Dr. Jinzi J. Wu, Founder, Chairman and CEO of Ascletis.

    [1] Jeong-Joong Yoon, Mart Toots, Sujin Lee, et al. Orally Efficacious Broad-Spectrum Ribonucleoside Analog Inhibitor of Influenza and Respiratory Syncytial Viruses. Antimicrob Agents Chemother. 2018;62(8):e00766-18.




    About Ascletis

    Ascletis is an innovative R&D driven biotech listed on the Hong Kong Stock Exchange (1672.HK), covering the entire value chain from discovery and development to manufacturing and commercialization. Led by a management team with deep expertise and a proven track record, Ascletis focuses on three therapeutic areas with unmet medical needs from a global perspective: viral diseases, non-alcoholic steatohepatitis (NASH) and oncology. Through excellent execution, Ascletis rapidly advances its drug pipeline with an aim of leading in global competition. To date, Ascletis has three marketed products, i.e. ritonavir tablets, GANOVO® and ASCLEVIR®, and 23 drug candidates in its R&D pipeline. The most advanced drug candidates include ASC22 (HBV functional cure), ASC10 and ASC11(oral small molecules for COVID-19 treatment), ASC40 (recurrent glioblastoma), ASC42 (PBC, primary biliary cholangitis), and ASC40 (acne).

    For more information, please visit

    China Expert network
    PR Newswire is the premier global provider of news release distribution and multimedia platforms that enable marketers, corporate communicators, sustainability officers, public affairs and investor relations officers to leverage content to engage with all their key audiences. Having pioneered the commercial news distribution industry since 1954, PR Newswire today provides end-to-end solutions to produce, optimize and target content – from rich media to online video to multimedia – and then distribute content and measure results across traditional, digital, mobile and social channels. Combining the world's largest multi-channel distribution and optimization network with comprehensive workflow tools and platforms, PR Newswire powers the stories of organizations around the world. PR Newswire serves tens of thousands of clients from offices in the Americas, Europe, Middle East, Africa and the Asia-Pacific region, and is a Cision company.