Ascletis Pharma Inc. announced that the China National Medical Products Administration (NMPA) has approved the Investigational New Drug (IND) application of ASC10, an oral inhibitor drug candidate targeting RNA-dependent RNA polymerase (RdRp) for COVID-19. Ascletis is China's first biotech company which has obtained IND approvals of an oral RdRp inhibitor from both China NMPA and the U.S. Food and Drug Administration (FDA). ASC10 is an oral double prodrug which has a new and differentiated chemical structure from the single prodrug molnupiravir.

After oral administration, both ASC10 and molnupiravir are rapidly and completely converted in vivo into the same active metabolite ASC10-A, also known as ß-D-N4-hydroxycytidine (NHC). ASC10 was discovered and developed in-house. Ascletis has filed multiple patent applications for ASC10 and its use globally.

ASC10 oral tablet formulation for the clinical study was developed with in-house proprietary technology of Ascletis. By applying a double prodrug strategy, ASC10's permeability in Caco-2 cells (human colorectal adenocarcinoma cells) and active metabolite exposure in monkeys reached 3.2-fold and 2.1-fold of molnupiravir's, respectively. In the SARS-CoV-2 infected mouse models, ASC10 at 240 mg/kg twice daily led to a 4.0 log reduction in viral titer in lungs, equivalent to molnupiravir at 500 mg/kg twice daily[1].

Preclinical studies demonstrated that ASC10-A has potent cellular antiviral activity against Omicron variant (EC50 = 0.3 µM), Delta variant (EC50 = 0.5 µM) and wildtype virus (EC50 = 0.7 µM). It also suggested that there were no drug-drug interactions between ASC10 and other common medicines. Ascletis is actively communicating with regulatory authorities to explore the possibility of further accelerating the clinical development of ASC10.