K777

K777 is a potent, orally active and irreversible cysteine protease inhibitor. K777 is also a potent CYP3A4 inhibitor with an IC₅₀ of 60 nM. K777 irreversibly inhibits Cruzain, the major cysteine protease of Trypansoma cruzi, and cathepsins B and L. K777 is a broad-spectrum antiviral by targeting cathepsin-mediated cell entry. K777 inhibits SARS-CoV and EBOV pseudovirus entry with IC₅₀ values of 0.68 nM and 0.87 nM, respectively^[1][2][3]. IC50 & Target:Cysteine protease^[1][2][3]
IC50: 60 nM (CYP3A4)^[3]
CCR4^[3] In Vitro:K777 (K11777) can inhibit entry driven by other viral envelope proteins, including HIV-based pseudotypes bearing spikes from coronaviruses (SARS-CoV, HCoV-229E, NL63, MERS-CoV) or glycoproteins from filoviruses (EBOV, SUDV, TAFV, RESTV, BEBOV and MARV).
K777 inhibits SARS-CoV, HCoV-229E, NL63, MERS-CoV, EBOV, SUDV, TAFV, RESTV, BEBOV, MARV and Nipah pseudovirus entry with IC₅₀ values of 0.68 nM, 1.48 nM, 6.78 nM, 46.12 nM, 0.87 nM, 1.14 nM, 2.26 nM, 3.37 nM, 5.91 nM, 1.9 nM and 0.42 nM, respectively.
In contrast, 100 nM K777 does not inhibit infection mediated by envelope glycoproteins from an alphavirus (CHIKV), a rhabdovirus (VSV), a flavivirus (HCV), the retroviruses MLV-A and XMRV or two arenaviruses, Lassa and Junin virus^[1].
K777 alone demonstrates up to ~ 70% inhibition of 229E-S-mediated transduction. Simultaneous treatment with Camostat and K777 increases inhibition to ~ 90%. Similar inhibition patterns are obtained using the human intestinal epithelial cell line Caco-2, which express endogenous TMPRSS2 and cathepsins^[1].
In Vivo:K777 (K11777; 35-105 mg/kg; oral administration; twice a day; for 10 days; C57BL/6 IFN-γR-KO mice) treatment rescues mice from otherwise lethal infections^[3] .