China-based firms CSPC Pharmaceutical Group Ltd (HKG: 1093) and Ascletis Pharma Inc. (HKG: 1672) both announced receiving the green light from the National Medical Products Administration (NMPA) to carry out clinical trials for their respective SYH2055 and ASC11, both inhibitor drugs targeting 3-chymotrypsin like protease (3CLpro) for COVID-19.
Market Landscape and Competitors
Fineline Info & Tech data shows that multiple small molecule 3CLpro inhibitors have been approved for the clinics in China, including Cosunter Pharma’s GST-HG171, Zhongsheng Pharma’s RAY1216, Frontier Bio’s FB2001, and more. In addition, Junshi Bio/Vigonvita’s VV993, Hansoh Pharma’s in-licensed GDI-4405, and Everest Medicines’s in-licensed EDDC-2214 are under development as well.
SYH2055: Preclinical Results and Advantages
The preclinical study has shown that SYH2055, a Category 1 chemical drug, has strong and broad-spectrum antiviral activities in Omicron BA.4, BA.5, and other dominant variants. In the animal model infected with COVID-19, it significantly reduces the viral load in the lungs and significantly improves pulmonary inflammation, which is superior to the same dose of nirmatrelvir. SYH2055’s pharmacokinetic properties in vivo in rats and cynomolgus monkeys were significantly improved compared with nirmatrelvir, which is expected to circumvent the situation that nirmatrelvir must be used in combination with ritonavir. In addition, SYH2055 also performed well in the pre-clinical safety evaluation.
ASC11: Potency and Development Plans
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 with 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. Ascletis Pharma expects to conclude a Phase I study for the drug in 2023, designed to determine safe and efficacious dosage for a pivotal Phase II/III clinical study and whether it needs reinforcement with ritonavir.
Paxlovid: Current Standard of Care
Paxlovid (nirmatrelvir/ritonavir), US major Pfizer’s COVID-19 combination drug, is recommended by the National Health Commission’s ninth COVID-19 diagnosis and treatment plan.-Fineline Info & Tech
