--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

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. Ascletis obtained the approval of conducting a Phase IIa clinical trial for ASC10 to treat RSV infection from the U.S. Food and Drug Administration in January 2023.

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.

Globally, RSV affects an estimated 64 million people and causes 160,000 deaths each year^[2]. 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^[3].

"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 China NMPA 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.