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Mpro Inhibitor STI-1558

Targeting the virus main protease (Mpro): interrupting virus replication

Jeong, G. U., et al. (2020). “Therapeutic Strategies Against COVID-19 and Structural Characterization of SARS-CoV-2: A Review.” Frontiers in Microbiology 11(1723).

STI-1558 is designed with the following properties:

  • STI-1558 is a prodrug, and its active form AC1115 binds to Cys-145 of catalytic domain of Mpro , which is 100% conserved in all SARS-CoV-2 variants, and achieves a broad-spectrum anti-SARS-CoV-2 activity including against the original Wu Han/Washington strain as well as the predominant variants of concern (VOCs), such as Delta and Omicron.
  • Oral bioavailability up to 76% with fast absorption and enhanced drug exposure in plasma allowing early treatment of COVID at home by oral administration.
  • Improved human liver microsomal stability to avoid using CYP34A inhibitor to increase the plasma exposure allowing for standalone treatment with low risk for drug interaction.
  • A drug product with robust formulation, stability and large-scale drug substance manufacture with controlled cost allowing for global accessibility and application

STI-1558 clinical trials

  • Phase I trial in Australia: May, 2022
  • Phase I/II trial in US: June/July, 2022
  • Phase II/III trial global: Sept, 2022