Ascletis Pharma Inc. announced dosing of 4 healthy subjects of the first cohort in multiple-dose escalation Phase I clinical trial of oral 3-chymotrypsin like protease (3CLpro) inhibitor ASC11 in combination with 100 mg ritonavir tablets for COVID-19. The Phase I clinical trial is expected to enroll 72 healthy subjects, including 60 subjects in single-dose escalation cohorts and multiple-dose escalation cohorts, and 12 subjects in food effect trial. The enrollment is expected to be completed in the first quarter of 2023.

Among the aforementioned 60 subjects, 32 subjects will be randomized into 4 cohorts to receive escalated multiple doses of ASC11 (in combination with or without 100 mg ritonavir tablets) or matching placebo twice daily (BID) for 5.5 days. The clinical trial is a randomized, double-blind and placebo-controlled study to evaluate the safety, tolerability, and pharmacokinetics (PK) of ASC11 in combination with 100 mg ritonavir tablets in healthy subjects. The aforementioned 12 subjects in the food effect trial will be randomized to receive ASC11 in combination with ritonavir tablets twice (fed or fasted) to evaluate the food effect on PK of ASC11 in combination with ritonavir tablets in healthy subjects.

In antiviral cellular assays with infectious SARS-CoV-2, ASC11 demonstrated much higher potency against SARS-CoV-2 than other 3CLpro inhibitors including Nirmatrelvir, S-217622, PBI-0451 and EDP-235. ASC11 remains potent antiviral activity against various popular Omicron variants such as BA.1 and BA.5. In the animal model with infectious SARS-CoV-2, ASC11 also showed potent antiviral activity. ASC11 is an in-house discovered oral small molecule drug candidate using various proprietary technologies including molecular docking.

Ascletis has filed global patent applications for ASC11 and related compounds and their use in viral disease.